Model 1 Sales 300 whisper upper function problems

[300whisper_newbie]

Jripper Wrote :
I just purchased a Model 1 Sales 300 fireball upper in a 16 " CAR configuration. It looks like a well made piece, but when I went to shoot it it would not cycle the action with any of the 3 corbon factory loads (220 subsonic, 125 and 150 supersonic). It appeared that there was not enough gas pressure to make it work. I have a JP adjustible gas block on order, and a reduced poundage buffer spring. Should the JP gas block take care of the problem, or is there any other modification/change in the gas system I need to make?

The bolt locks up somewhat tight, but otherwise looks like it is in working order.

Thanks

[300whisper_newbie]

QuarterBore Wrote :
Because it is a brand new upper, you may be experiencing some problems due to minor flaws in the metal work... You might try working the charging handle for an extended period of time and then lube things up a little to see if that helps...

If the problem is short stroking, I think you will likely need to have the gas port opened slightly and then use an adjustable gas system to alloy you to adjust the gasses for the specific load you want to use.

Another move done by many people is to relocate the gas port to the pistol location to allow for a longer gas pressure period but that is a more complicated mod...

I hope that someone else will post to share their experiences but the above is the general fixes that I have seen done over the years and these solutions seem to work for most people.

[300whisper_newbie]

Jripper Wrote :
Thanks for the help suggestions. I got my JP adjustible gas block last night, and will try to install it this week. Any idea how much I can open up the gas port? Do I just use a standard drill to do this, or will it leave a burr in the barrel?

I worked the bolt quite a bit, but it still looks like it needs more gas flow. The bolt unlocks with the 125 corbon load, but not enough to eject the empty or pick up a live round.

Very cool cartridge, though, and well worth the work getting the gun set p. I also have a Contender barrel on order, as I have learned that the round is Illinois deer legal (one of the very few bottle neck pistol calibers that fit their requirements: case length less than 1.4 inches, minimum .30 caliber, and make at least 500 ftlbs of energy at the muzzle from a factory published load.)

thanks
Joel

[300whisper_newbie]

Patriot762 Wrote :
Hey,

I tried the JP adjustable gas block with an enlarged gas port on a 16" barrel.

I couldn't get any functionality with any subsonic loads. 180 gr bullets, H110, and one other fast powder.

I was able to get it working with an H335 supersonic load. More pressure being built further down the barrel.

Since there's no real reason to have a 300 that can't be used subsonic, i had my smith install a pistol length gas system.

I haven't played with a lot of different loads, but it functions every time so far with subsonic. I probably should get an adjustable gas tube or new gas block when i get my suppressor, so the added back pressure doesn't beat up my receiver. (I used the JP gas block on another rifle)


your best bet is probably to shorten your gas system and use the JP block. Just make sure that the handguard you use is big enough to squeeze the gas block under. Mine had to be milled down quite a bit to fit.

Badger ord might be working on an adjustable block with a lower profile. Or you could go with the Fulton adjustable tube.

It's easy to fill in the old carbine gas port. you can't even tell where it was on my rifle.

Good luck, and write me if you have any other questions.

JC

[300whisper_newbie]

Jripper Wrote :
Thanks for the input. It looks like I will have to go with moving the gas port to the pistol position, as I tried the over size port, and still no go. It did get a lot close, and I could go a little larger, but I don't think it will ever work with subsonics in that position. Does anyone have any specifics, or websites where I can get them, as towards where the new port is locate, and how, and with what, do you fill the old port?

I think my gunsmith friend and I can do this, if we know the particulars.

Thanks
Joel

[300whisper_newbie]

300whisper_newbie Wrote :
I was about to purchase a model1 upper in 300 whisper but now you've got me second guessing my decision. When I spoke to them on the phone they told me that their upper would cycle subsonic loads.

I'll have to talk to them again tommorrow, could you post the exact ammunition you used, any information on the box such as FPS or lot#?

I'll try to get them to tell me what ammo they use to testfire their uppers.

--Chris

[300whisper_newbie]

Jripper Wrote :
Chris,
I am using Corbon factory ammo. The subsonic uses a 220 grain bullet at 1040 fps (factory specs). My upper would not even work with the supersonic ammo straight from the factory. The overall fit and finish is fine, and I still think that for the money, it is worth the modifications necessary to make it work. It appears that it is manufactured with the standard .223 gas system/port location, etc.

I am still working the kinks out of mine to make it work.

I am in the process of trying to figure out how to fill the old gas port, and where to drill the new one.

From my research, any upper short of the SSK one will need these mods (Olympic being the only other one I could find, and they are currently out of stock)

Anyway, if you compare cost, the Model 1 is still going to come out ahead even after the modifications.
If you have the money, by all means buy the ssk. I did not, so I could not go that route.

And a little fiddling does not bother me to make it work. I like doing that sort of thing, and have a couple of friends who are gunsmiths who can help me with it.

I'll keep posting my progress on this forum.

Joel

[300whisper_newbie]

300whisper_newbie Wrote :
Jripper,

Yeah I know what you mean, I was planning on purchasing one and seeing if it will function by itself. If not I was planning on enlarging the standar CAR position gas port. I think it would be easier to open the gas port in the current location rather then fill and drill and a new one.

--Chris

[300whisper_newbie]

Jripper Wrote :
Chris,

I tried drilling the hole larger. I went from .060 to .085, and it will not even begin to function with subsonic, altough it is getting close with super sonic. I spoke with techs at JP enterprises, and they advised I could go to .110, or .120 max, but I am not sure if it will help that much. I think I could make it work with supersonic, but I don't know if drilling it out would ever help the subsonic loads.

I may try to go a little larger, and see where I end up.

If it doesn't work, I will just go with the re-location.

I'll kept posting what I find out.

Joel

[300whisper_newbie]

300whisper_newbie Wrote :
talked with model1 today. They claim that their uppers cycle the Corbon subsonic they have in house correctly.

I guess I'm going to pull the trigger and get one. I bought a 6mm PPC upper from model1 in the past and have had no trouble with it so far. I'll keep you guys updated, worst case I'll be debugging with Jripper

Jripper, is your upper short stroking? Does the bolt unlock from the barrel extension, or is it locked in battery? Did you purchase the bolt/carrier with the upper or are you swapping with another upper?

--Chris

[300whisper_newbie]

QuarterBore Wrote :
You guys keep it up and I will be joining you...

http://www.model1sales.com/item-detail.cfm?ID=UCO300&storeid=1&image=u16carpost3.g if

Which configuration did you go with?

[300whisper_newbie]

300Whisper_newbie Wrote :
I just placed my order:

16" CAR 300 Fireball 1:8" Twist A2 FlashHider
-A3 Flattop with gas block sight base
-Fluted Free Float Tube
-Bipod Stud
-Jard single stage 1.5lb trigger
-Dedicated Bolt/Carrier

They told me it will take 2 weeks to build

--Chris

[300whisper_newbie]

Abyssdncr Wrote :



Chris,

I tried drilling the hole larger. I went from .060 to .085, and it will not even begin to function with subsonic, altough it is getting close with super sonic. I spoke with techs at JP enterprises, and they advised I could go to .110, or .120 max, but I am not sure if it will help that much. I think I could make it work with supersonic, but I don't know if drilling it out would ever help the subsonic loads.


Joel,

I've got a M1S in .300 Fireball and thus far have had no problems at all. When I ordered I asked what the gas port diameter is and was told .125".
I haven't checked this with a drill bit, but the visual inspection of the port doesn't contradict this statement. I imagine you'll need to open up a bit more. I've had no problems with Cor-Bon 125 gr HP. All else has been my home rolled stuff. The lightest load thus far has been 180 gr RNSP over 10.5 gr. H110. This cycled perfectly. I've since added an adjustable gas tube to turn the gas down for my deer loads (19.5 gr. H110 under 125 gr. Nolser Ballistic tip in Win. .223 Rem brass).

My only complaint about the M1S purchase is that they installed my front sight base canted off about 5 degrees and refuse to fix it... I guess you come to expect some problems with the low bidder route, but overall it's a excellent setup.

Good luck,
Brian

[300whisper_newbie]

Jripper Wrote :
Thanks for all the replies.

Yes, my upper is short stroking. It unlocks the bolt, and since I opened up the gas port to .085, it ejects but the bolt sticks about 1/2 way back. I also put in a reduced power buffer spring from Wolff. The gas port in my barrel was only .060 when I started. If it supposed to be .125, then that may be my problem. I will try opening it up that to about .120, and see if that works. I can fill the port if necessary , at either diameter.

Yes, the bolt came with the upper. It was a tight fit, and I have worked it quite a bit, and it is now working smoother.

I will keep everyone up to date on my progress.


Also, A 1 sales had mine to me in about 1 week, I got the 16" CAR with threaded barrel/flash hider and free float hand gard. I actually went a head and got the full kit, short of the lower.

Please keep up the good input.

I am not going to give up on this project, as the cartridge is just too darned cool!!!

Thanks again everyone.

[300whisper_newbie]

Jripper Wrote :
Update:

I opened the gas port to .125 (approx.), and it now works fine with both corbon supersonic loads. It ejects the subsonic load, but the bolt hangs up about 1/2 way back. I may open it up just a little more I may also see if I can my own subsonic load to work. Any suggestions for a powder for subsonics with 180 to 220 grain bullets?

Thanks
Joel

[300whisper_newbie]

Jripper Wrote :
Update:

I have opened my gas port up to .135, which is about as big as the hole in the gas block. It will work with both corbon supersonic loads, and almost works with the corbon sub sonic (ejects, bolt sticks about 2/3 way back). However, after looking at some of the posts in other areas, it looks like the Corbon load may be very slow. I need to chrono out of my gun. i have some 240 sierras coming and will try my own subsonics, but I bet I can get it to work. I still haven't had time to work on load (Christmas, sick relatives, etc.). I will keep you up to date for anyone considering the purchase of the Model 1 sales upper. Opening the gas port is not hard. It only requires a number drill bit set, a hand drill, and some cutting oil. I did put a old steel cleaning rod inside the bore when drilling, so that I would not go too far and damage the opposite side of the bore.

Joel

[300whisper_newbie]

QuarterBore Wrote :
Did you use any jig or a drill press to help you keep square? I would love to see you post a "How-To" post on opening a gas port if you would be so kind!

QB

[300whisper_newbie]

Jripper Wrote :
I am not a professional gunsmith, altough I play one on TV. Actually, I just hang around with a few, and have picked up little things here and there. I am not saying that a drill press would not be better, but since you are making an already existing hole bigger, it is not to hard to do.

A man from JP Enterprises tech line gave me a few pointers on this. Basically, figure out how big your existing hole is, using a numbered drill bit set. Then start enlarging by going not more than two numbers larger. The man from JP said that you can use a drill press, but is not necessary. The advantage there is you can set a stop to keep from going too far.

However, what I did was put an old, steel cleaning rod through the bore. This kept me from over drilling, and scoring the opposite side of the bore. It also let me know when I drilled all the way through the side I wanted to drill, as when I hit the rod, it would move. Use plenty of cutting/tap oil. I used Tap Magic (which is what the JP guy also reccomended, and I happened to have on hand). It goes a little slow, as the barrel metal is very hard. Just keep moving up two bit sizes at a time until you get it where you want.

JP told me to not go above .120, but they were not familiar with the .300 whisper cartridge. One of the people that replied to my message said that Model 1 told him that it was .125. I went to .125, and was not quite satisfied, so I went one more size larger. Since I was using an adjustible block, it really does not matter, as I can always shut it back down.

Make sure to clean all the metal filings from the bore.

It will leave some burrs around the port, but don't worry about this, for as soon as the first shot or two is fired, it smooths it self out. You can not tell the difference now.

The strange thing is that from the factory, the hole was only .060. But there was a circle around the hole of approx. .125. It appears like it was supposed to be drilled to that diameter, but they used the wrong bit!!!

I did break the tip off of one bit during the process, and had to punch it down into the barrel, and push it out of the bore. Other than that, it was not big deal.

And this from a guy who can't make toast!!!

Don't be afraid of the Model 1 uppers/products. I think they are a bargain.
Hopefully, I will be able to give you some chrono figures and groups soon.

Joel

[300whisper_newbie]

300whisper_newbie Wrote :
My Model1 300 whisper should be delivered tomorrow afternoon I'll post a review of the quality/fit/function etc..

--Chris

[usma89]

When I was first starting with the 30/221 I bought a M1S upper. I had to open up the gas port( I had it done by K2). It functioned fine with subsonics after that. I also used a carbine lower.

[Jason280]

I also just got in the Whisper game. I have a flat top 16", and it appears to be a M1S upper. It functions 100% w/ CorBon 150gr SP's, but it almost seems like it may be getting too much gas. I am going to measure the port tonight and see what the diameter is. I recently loaded some 125gr BT's and 125gr Bergers, but I haven't gotten a chance to shoot anything. I've also loaded 25rds of subsonic 240's w/ AA No 9 and 25rds with H110. I will definitely give an update when I shoot them on Wednesday.

I'm pretty sure I will eventually go with an adjustable gas tube, especially after my supressor paperwork clears.

[jripper]

Update:

I still can not get the model 1 to work with subsonics. It will not work with corbon factory, or with 240 sierras using W296. In fact, I have the 240s all the way up to 1200 fps, and it still does not cycle. Works fine with supersonic 125s, corbon factory and rem 125 psp with 18.5 W296. I may try another powder with the 240s. Any suggestions from anyone? Faster or slower?

[300whisper_newbie]

Jripper,

Sorry to hear about your continued problems. Since the rifle is not auto-loading can you see how far the bolt carrier is coming back? I think my carrier is almost coming back far enough and just missing by a 1-1.5mm. The rounds in my mag are scratched from just below the lip where the carrier stopped and went back into battery. I cycled mine by hand and think she'll cycle as the carrier/upper wear in a little. I'm in Cali until sunday so I could not bring the rifle to play with it here, I'll try to shoot some more next week and report back on my progress.

FYI: I'm loading 220 sierras over 9.1gr of H110.

--Chris

[Quarterbore]

I am curious if you have looked at some of the other variables...

Have you tried other powder combinations? With the 300 Whisper in a semi-auto the problem isn't the velocity of the bullet but instead the amount of gas that is left to cycle the action. It may be that the powder you are using just doesn't have enough Ooommpp to cycle things...

Also, are you using this with a Rifle or CAR stock?
What buffer are you using (ESP if it is a CAR - Std, H-Buffer 9mm)
Have you considered modifying the buffer spring a little to take off some of the weight?

I would try other powder combos first but there are a couple other areas that could be changed in this system if needed...

[300whisper_newbie]

I am curious if you have looked at some of the other variables...

Have you tried other powder combinations? With the 300 Whisper in a semi-auto the problem isn't the velocity of the bullet but instead the amount of gas that is left to cycle the action. It may be that the powder you are using just doesn't have enough Ooommpp to cycle things...

Also, are you using this with a Rifle or CAR stock?
What buffer are you using (ESP if it is a CAR - Std, H-Buffer 9mm)
Have you considered modifying the buffer spring a little to take off some of the weight?

I would try other powder combos first but there are a couple other areas that could be changed in this system if needed...

QB,

I haven't thought about the buffer spring untill you mentioned it. I'm running my 300 whisper upper with a full length rifle stock/tube. I don't have a CAR lower but a buddy has an m4gery that I could borrow his lower to see if that helps at all. I would be interested to see if jripper is also running with a full length rifle buffer.

--Chris

[jripper]

Latest Update:

I got my Model 1 to function with 240 sierras and AA 1680. It was SSK's reccomended load. I am using a full stocked lower, but am using a reduced power buffer spring, made by Wolff, available through Brownells. However, I think it will work with the load with the stock spring. It looks like slower powders are better. I tried AA #9 and W296, and could not make either one work with either load (W296 load did pick up a new round one time, and will actually work the bolt forward and back, but does not pick up a new round, in other words, very close to working).

I also have a m4 stock, but do not have a lower to put it on yet (Indianapolis gun show is coming soon!!!) so I can not comment on that making a difference.

My loads with the AA 1680 only Chronographed 850 fps, so I will be able to bump up my charge a little. (outside temperature was only 39 degrees, and very damp). I would think that any slower powders would probably work, also. I suppose the pressure peak is farther down the barrel with the slower powders.

This does not bother me a bit. I can live with subsonics with only certain slower powders, if it keeps me from going to the hassle and expense of moving the gas port back to the pistol position.

I'll load up some more round with 1680 and see what I can accomplish.

After I finish these 240's, I plan to get some Sierra 220s, to work with. With the W296 load, they were not stablizing in my gun, even though model 1 says it has a 1 in 8 twist. The 220 corbon load, seemed to stalize OK, but the 240's were going into the target sideways at 25 yards.

I did not shoot any of the 240s with the other powders at a target, so I can not say if they would be any different than the 296 rounds, but I don't see why they would be.

I 'll keep posting as I make progress. I am also working on a load with the 296 and 168 BTHP. SSK claims that can make 1950 fps, and if they do, they will make IPSC/USPSA rifle major power factor.

If they do so safely, there could be a whole new market for this round.

Joel

[Zed Stewart]

I would imagine that 850 is to slow to stabilize the 240s. What I have gathered from all sourses is that the 240s are just stable enough to work, at range, with a 1-8" twist. this is why JD Jones says they kill stuff a lot better than the paper ballistics would indicate. (More on that later.) I wouldn't give up on them until you run some at at least 1000 fps.

Just my 2 cents.

[sharpshooter33]

Hi all,
I have had my Model 1 300 Fireball for about 9month. Only have about 15 rds thru it. All rounds are 150gr Corbon. The 1st two or three didn't quite function the bolt but since then I've adjusted my Adjustable gas tube and it's functioned great.

I haven't tried the subsonic yet. Was waiting until I had good barrel breakin.

I am interested now if it will function with the subsonic since I've read this.

My plan is to suppress it this year and I'm looking a Lauer Weaponry right now. Wonder if the suppressor will affect the function also?

I may go out this week and run 5 rounds check with subsonic and check my function.

Also liked the full auto 300Whisper video posted on QB website! :lol:

[sharpshooter33]

Well, I'm glad QB told me to check the forums here. I went to the range today and fired 4 rounds of 220gr Corbon Subsonic. I quit at for because I figured why waste ammo until I got it fixed. My Model 1 I purchased last year some time around summer. I purchased barrel only and put it together my self with upper and adjustable gas tube.

I've now fired 20 rounds of 150gr Corbon without flaw except for the 1st 2 rounds. I use a M16 bolt carrier which is heavier than the AR15. Standard stock and buffer setup. I was concerned originally thinking I may not have lined up my gas port with the block. I'm using a rail fron gas block with locking screws and I wasn't sure that I was getting it exactly over the hole. I have not gaged my port, however after reading this thread I'm thinking I will. I took 5 rounds of 220gr Subsonic to the range and fired them for effect. 1st one almost pulled the bolt back half way. Most didn't pull it enough to remove the case from the chamber. It was about 20 degrees out side and I forgot my allen wrench to adjust the gas system so I didn't stay around the range and tinker with it. I was pretty much convenced by the posts here it would be useless anyway. I'm going to go back and check the hole size and make sure the gas block is aligned properly. Jripper looks like he has had more trouble than most getting his M1 300/221 to work.

Just thought I'd drop a line here and welcome myself to the club.
:shock:

[jripper]

I found some very good information of AR15barrels.com. A retail sight that sells manufactures/sells 300-221 barrels. I believe it is under his FAQ sections, where he states that he also opens up his gas ports to .120, and says that most .223 barrels are around .080. He also says that if the customer wants to use the barrel to shoot subsonics, he puts the gas port at the pistol position, to allow use of all types of ammo.

Opening up the gas port is not that big of deal, as I previously posted.
To move it involves TIG welding the old hole shut, re-drilling the hole in the pistol position (which I am not sure exactly where that is), modifying or replacing the gas tube. You then have to make sure your gas block is going to fit under your handguards (modify or replace most likely). Then, if using a free float, you will have to drill a hole into the handguard to access your adjustible gas system.

There are a few other possibilities that may help. I have tried a reduced power Wolff buffer spring, altough in my case, it did not seem to make much difference(if the loads are real close to cycling, it may help). These spring cost less than $10 (for the rifle length buffer. I still haven't tried my with a CAR stock and buffer, as I am still trying to get a second lower).

JP makes a lightened bolt carrier, that may make cycling easier, and help the loads to work (caution though, use the tactical carrier, and not the match carrier (I believe it is aluminum) as it is only for use with the JP trigger/lightened hammer set). These are $100 plus, and I have not tried them myself, but JP makes excellent products, and have top notch customer service.

There is also a product called a pig tail gas tube. I don't know who makes them, but Brownells sells them. They are supposed to lengthen the pressure curve. This might also help, as I previously posted, I have had luck with slower powder and subsonics. These are $80 plus.

AA 1680 seems to work with subsonics for me, and that if fine, as I primarily want the gun to function with supersonics, as Illinois makes getting a supressor extremely exspensive, if not almost impossible.

My bolt also has broke in quit a bit, and I have not tried the Corbon Subsonics since then, as I shot all but one single round. I can not tell if they would now work.

If you reload, try some loads with the AA1680, or slower powders, unless you absolutely have to be able to shoot factory corbon subsonics.

I suspect that you will have to open the gas port, regardless.

Good luck. Keep posting, as will I, and we will compare our progress.

By the way, I was shooting sub 1/2 inch groups with remington bulk 125 gr psp at 50 yards, and pretty sure it will shoot 1 moa at 100, but was using a Holosight, and the best I could keep them in was 1 1/2 inches.

This is plenty good enough for a 325 upper assembly.

Joel

[mtb8r3]

Hello all.

Sorry I have kept quiet so far, but I lacked anything of substance to say. Just been browsing the site and learning what I could about the Whisper.

Two weeks ago, I recieved my first .300 ar barrel form model 1 sales. The package was shipped from Il to MO for $18. I called, and they said they made a mistake (that was the shipping on a complete upper..????) Anyway, I am waiting on the $8 they are suppose to re-credit.

For anyone wishing to go this rout and build their own, pay attention. Their 300 barrels have a different thread for muzzle devices! No where do they mention this, but your stock AR flash hider will not work. I called up, and they said they would ship one out for an additional $20, plus $7 PHI. These guys relly need to get on board with the USPS.

Anyway, I assembled everything last night, and headed to the range today. As everything else I reload is either mid-level pistol, or high power rifle, I didn't have any magnum pistol powders on hand. I decided to go with H110 due to its versitility, and loaded up some loads. Using info found on line, I fixed up 2 subsonic, and one supersonic load (210g berger, 200g Lapua RN, and 165g Barnes solid.... Hey, its what I had laying around). Thanks to the discussion here, I was not supprised when nothing cycled. The hot 165's would half-extract, but the rest didn't even unlock. Now, granted, I don't have a chrono, and it is below zero outside, so velocities were likely below what they should have been. So I went home.

Got into the gun room here, and started reading over the other threads. I checked my port diameter, and sure enough, just over .1285 (#30 fits). I tried some 200 grain bullets, but jumped the powder from 9.1 to 11gr. Went outside and proceded to make some BIG holes in the earth.... Still not cycling. I dedided to try the non-adjustable gas system off my standard AR carbine....Still not cycling. The bolt will half extract, and stick.

Scratch head....Idea. I looked at the bolt/carrier I was using. While it didn't cycle roughly, it was still just a parkerized finish. I pulled the chrome plated bolt from my other carbine (Matte silver type), and loaded up 3 more rounds. You can appreciate my joy when I watched 3 little pieces of brass jump smartly from my ejection port. Looks like there is hope after all.

Now that things are working, I can begin some real testing. Sorry if I was a bit long winded, by I just wanted to share in the frustration that some of you have experienced. I hope that this was helpfull to at least somebody, and will keep you all posted with future range reports.

[mtb8r3]

Just conducted another test. Looks like 11 g is a bit hot. 10 grains looked good in pressure signs, but only cycled completly about 50% of the time. I think I will look somewhere in between for this bullet (200 gr Gameking). As soon as I get access to a chrono, I will provide addiitonal data.

[Greywuuf]

about the "odd" thread size on the muzzle. I called and asked about that. They do it on pourpose to keep us from hurting ourselves. It is threaded 1/2"x36 tpi which is the same as the 9mm ( and 7.62x39 I think ) that is to keep us from screwing a .223 flash hider on there and trying to shove .308 bullets through it .

look around you might find something you like better that is compatible.

[Zed Stewart]

I guess they do not realize that a standard A1 or A2 hider is plenty big for a .30 caliber bullet. A .308 round will go through up to the shoulder.

[jripper]

I can kind of see their logic on that one. Altough a standard A1 or A2 flash hider may be big enough for a .30 bullet, some of the various .22 muzzle brakes that you could install may not be.

I still wish they would have used the standard AR thread though.

[jripper]

Update:

I think I have this thing figured out. It will run reliably with 220 and 240 graind Sierra's, subonic. Put 20 rounds of 11 gr. AA 1680 and 220 Sierra bullet through last Sunday, and ejection was quite positive. Did not chronograph, but they were very quiet, and almost had to be subsonics. I did chrono the 240s with 10.3 g AA1680, and they were only going 850 fps (they did run, however).

The bolt has broken in, and works a lot smoother.

I am still using a full length stock and buffer tube, and have my JP gas block wide open.

Runs good with all supersonics that I have put through it.

Here is what I have concluded about this gun/round.

Bolt needs to be broke in fully (good tip, Quarterbore)

Gas port needs to be .120 or slightly larger.

Need to use slower powders within the reccomended range for this cartridge, to make it run with subsonics.

I didn't really mind the experimenting, as it has occupied me during the winter.

I still would reccomend the upper, with qualifications concerning what is necessary to make it run.

It is an economical way to get into the cartridge.

If anyone buys one, I would reccomend getting a upper without a bolt, and buying a chrome plated bolt from someplace else, however.

Joel

[300whisper_newbie]

Good to hear Jripper! I've just finished loading up about 100 rounds of 11gr h110 with 220 sierras on top. Hopefully I'll get a chance to run them through my upper this weekend. If they don't eject I'll pick up some AA1680 and see how that works.

Thanks for the info!

--Chris

[mtb8r3]

Let me know how that load works in your gun. As I mentioned eariler, 11g of H110 with a 200 gr Gameking had VERY bad pressure signs. The brass I attempted to reload would not even hold a new primer. I finally settled on 10.2g for reliable operation, though I still need to chrono it.

[300whisper_newbie]

Let me know how that load works in your gun. As I mentioned eariler, 11g of H110 with a 200 gr Gameking had VERY bad pressure signs. The brass I attempted to reload would not even hold a new primer. I finally settled on 10.2g for reliable operation, though I still need to chrono it.

Don't tell me that, guess I better watch for pressure signs on my 220s, would hate get a KB so early in the game :( What was your parent case? I was told that using 223 parent cases reduces the internal volume slightly which is why I used the 221 fireball brass. That could explain why you would be getting pressure signs early. I used 10g h110 with 220 SMKs and didn't see any pressure signs at all so far.

--Chris

[jripper]

Just for information, I went up to 12.0 grains W296 with 240s, and pressures were fine. It is very similar to H110. I can't remeber which brass I used. I guess each gun is different, as towards maximum loads.

[mtb8r3]

Sorry for the delay...
Yes, I was using .223 LC brass cut down. 10 gr with 210 Berger’s showed no pressure signs, but 10.2g was just beginning to flatten the primer (Winchester). You may be correct about case volume. If you get the chance, send me an average case measure of grains of water and I will post a comparison. The 10.2 gr load will eject, but not chamber another round. I am thinking that a slightly slower powder may be in order.

Now that I have had some time (and weather) to do some more testing, my 185 Lapua moly load with 10.2 g H110 is shooting 1" 10 shot groups at 100.

[Zed Stewart]

Just in case everybody doesn't know, H110 and 296 are the same powder. The minor differences in published loading data is from different lots of powder being compared, not actually different powder.

[jripper]

I always figured they were, but could never get a positive answer.

Thanks

[sharpshooter33]

hello gang. I've been outta the loop for awhile working on other projects. Now that I've got some time I went to the range with a wrench for my adjustable gas tube on my M1S 300/221 barrel.

I am using a 16" M1S 300/221 barrel, standard stock and buffer situp and AR15 bolt carrier.

On last report I tried the 220 Corbon and found as you did it didn't cycle the bolt. I opened my adj gas tube all the way up today and it ejected the spent casing, but would not pickup a new round. I'm going to take the barrel off tonight and measure the gas port. If it comes out under .120 that will be my next step. I'll open it and send it off to have it threaded. I'm working on this for a suppressor project. Does anyone know how a suppressor will effect the function if any?

I'm assuming that there would be noticable function changes if it's functioning with 220gr before it should function after.

I'll let you all know what I have to do to get mine to cycle like a champ, but I agree with Jripper that for the $$$ these are a good buy. We also could help them out by letting them know about the hole diameter fix so future 300/221 don't suffer our problems and shoot the company down.

Thanks for everyones input here it has really helped me.

[sharpshooter33]

BTW I believe the threading is 5/8 x 24tpi?
If so it matches Bushmasters threading for there 308 rifles and they have a nice AK style brake to fit it.

I'm having my AR10T and 300/221 threaded 5/8 x 24tpi for muzzle brakes of that size and also a suppressor.

[sharpshooter33]

Hey I pulled my M1S 300/221 barrel off last night. The hole is around .118 I believe. I'm gonna open it and the hole in the block and tube up to .120+

Hey did anyone check the I.D. of the gas tubes. They are around .120 I think. If the port is opened up the gas won't flow any faster than the smallest point. Opening up the port wouldn't make any difference after about .130. I'm going to make sure mine is opened up to .120 to .130 then I'm gonna work on loads. The Corbon's shot 6" lower from 150gr to 220gr at 50yards. I don't have a Chrono either, but I'm thinking I can get mine working with subsonic 220gr if I use my own loads. I think Corbon 220 subsonics must be anorexic. Has anyone Chrono'd there load out of a AR15?

going shopping this week for some AA1680. Already have the 220gr and brass waiting for me.

Question the 11gr AA1680 for the 220gr tha Jripper is using, what type of cases are you using. I've got Federal, LC and 221.

Thanks
David

[jripper]

Thought I'd chime in again. I have been told that most tube are .120 inside. I think when I drilled mine out, that was the closet bit size that I had, as going over the inside tube diameter will not help. Also, if you look at ballistics of a 220 sierra at 1000, and a 150 grain at 2000, it is not suprising that there was that much of a change in point of impact. Also, make sure your bolt works freely. Mine was very stiff, and I think that makes a difference in how light a load it will cycle. I have not chronographed the corbon subs myself, but in another post on this sight, someone chrono them, and they only came in at 850 fps. My subsonic loads were loaded into Federal 223 brass, that I re-formed into 300 whisper.
I have also heard that putting a supressor on your gun will create more back pressure, and improve cycling, but I can not verify this, as I live the in Republic of Illinois, and can't own one.

Lastly, another post on this sight stated that the threads on the model 1 barrels were at 1/2 x36, but there again, I can not verify this myself.

Joel

[sharpshooter33]

AGT(adjustable gas tube) Has everyone been using one of these? I noticed when I disassembled mine to send the barrel off for threading that the gas tube is leaking at the adjustment block.

My 300/221 was close to cycling with the subsonic from Corbon. I'm wondering now if the gas tube could have been enough to make it not cycle fully.

Has anyone use a standard gas tube? I'm wondering if there is any problems with a standard tube. Does it create that much difference from subsonic to supersonic? I'm thinking of trying the standard gas tube. At this point the only advantage of the adjustable would be the ability to turn it completely off. I don't think the recoil/return gas on the supersonic rounds it that drastic that I really need the AGT.

Any opinions on this? :?:

[mac66]

Hello all-- I too have had ongoing problems with my .300 whisper. It is an AR-15 w/ a 16" barrel with the gas port in the carbine position. I first purchased a JP adjustable gas block and a "Pigtail" gas tube. It will now eject the empty (supersonic) and, about 50% of the time, chamber a new round. Subsonic rounds smokestack and/or fail to feed. After reading the above posts, I have been looking at the gas port diameter and will open it up to .125 this week. I also polished the chamber with my Dremel and Flitz to reduce any friction that may be contributing to the problem. I'll try to test fire this week. Thanks for the ideas.

[sharpshooter33]

mac66,
I would trade out the pigtail tube for standard. The pigtail will be doing the opposite of what you want. It is slowing the ejection. I could be wrong about that, but from what I understand the pigtail delays the gas operation. It was good for 7.5" AR15 barrels, but I'm not sure it a good idea for the 300 Whisper. Can anyone else provide info on the pigtail.

My understanding of the pigtail was that the bolt on 7.5" was either tearing away cases because there wasn't enough time before the case was being ripped from the chamber or it was sending it back too violently and ripping the cases.

Someone with an understanding or experience with this chime in.
Who's 300 do you have? Is it also a Model 1?
Hello all-- I too have had ongoing problems with my .300 whisper. It is an AR-15 w/ a 16" barrel with the gas port in the carbine position. I first purchased a JP adjustable gas block and a "Pigtail" gas tube. It will now eject the empty (supersonic) and, about 50% of the time, chamber a new round. Subsonic rounds smokestack and/or fail to feed. After reading the above posts, I have been looking at the gas port diameter and will open it up to .125 this week. I also polished the chamber with my Dremel and Flitz to reduce any friction that may be contributing to the problem. I'll try to test fire this week. Thanks for the ideas.

[mac66]

sharpshooter33,
The barrel was turned and chambered by Mike Orwan. The upper/lower and bolt carrier are Bushmaster. It has a standard length buttstock/spring. Shortly after I recieved mine Mr. Orwan began to place the gas port in the pistol position with better success from a wider range of sub/supersonic loads (per his website). I did initially try a standard gas tube with resultant failures to extract/eject. The rifle was basically a single-shot. Loads consisted of 125-190 grain bullets at close to maximum powder charges (supersonic loads) from Quarterbore or Accurate reloading data. I formed the cartridge form G.I. 5.56 brass. The only thing that really helped was a liberal coating of gun oil to the bolt carrier. This did improve performance somewhat. I will try a chrome carrier that I have to see if this makes a difference by friction reduction. All parts are almost new. Maybe the system need further "breaking in".
Last night I opened up the gas port to .125 and will try to put the rifle back together this week for a testfire early next. I'll review the powders that I loaded with to make sure they are on the slower end or the burn rate scale in effort to get the pressure to peak near the gas port. I put the Pigtail on hoping to lengthen the time the pressure was acting on the bolt carrier. I think the 5.56 round is rated at or around 60,000 CUP. The closest pressures in a subsonic round that I have seen is Accurate #2 that is no longer recommended for .300 subsonic loads. I thought the Pigtail might make up for the difference. We will see.
Anyways, thanks for the input. I'll get back to the board after I test fire next week. It sound like we all have about the same rifle configuration. Hopefully, we can find some common avenues to increase weapon reliability with sub/supersonic loads. Thanks again.

[jripper]

I'll summarize what I figure out during my trials with the model 1 upper:

Make sure you bolt works freely. Mine was very stiff, and once it broke in, it worked a lot better.

Opening up the gas port to .120 or larger.

Also, for sub sonics, slower powders work better: I found AA 1680 would cycle even with slow (850fps) loads, but W296 would not. I found either to work well with supersonics (125 grain and 168 grain).

I hope this helps.

Joel

[sharpshooter33]

Update:

I think I have this thing figured out. It will run reliably with 220 and 240 graind Sierra's, subonic. Put 20 rounds of 11 gr. AA 1680 and 220 Sierra bullet through last Sunday, and ejection was quite positive. Did not chronograph, but they were very quiet, and almost had to be subsonics. I did chrono the 240s with 10.3 g AA1680, and they were only going 850 fps (they did run, however).



jripper,
What primer are you using? I was looking at my Sierra book for pistol loads for the 300Whisper and it looks like there using Federal 250M which I think is a magnum pistol primer???? and they are using 11.7gr AA1680 in a Contender 10" to get 1000fps. Have you had a chance to Chrono the 11.0gr 220gr SMK load yet? I just worked up some 220gr SMK with 11.0gr AA1680 and CCI 400 SR primers. Let you guys know how they do on Friday. Don't have access to a Chrono so I won't be able to report on that.

SS33

[jripper]

No, I have not chronograph that load. I will probably do that this week. I believe I was using federal small rifle primers (standard, not magnum).
It burns every bit of powder, and I don't think a magnum primer is going to make much difference.

Right now, I have been going by sound and feel, and it would appear to be subsonic, but I'll Chrono to check.

I don't know about the rest of you, but I am seeing a lot of variation from listed loads, vs. what I am getting from my own gun.

I have also seen a lot of variance on what different people are calling a maximum load.

For instance, I am using 18.5 grains W296 behind a 125 rem. psp. Some people list a max load of over 21 grains. Past 18.5, I am blowing primers out of the cases!!!

I guess that it what can happen when working with a semi-wildcat.

Joel

[sharpshooter33]

Ok I've been tinkering with my 300/221 for awhile now. I have a load that duplicates the Corbon 220 Subsonics on paper, but does function my action. I'm using 11.0 gr of AA-1680. With my setup cases/primer/seat depth etc... I'm getting the same sight settings on the Corbon 220subsonics as I am with my 220gr subsonic reloads. The difference is mine cycle the action.

My AR cycled fine with lockouts on my last round. My problem and question is....That it failed to extract on several cases. I've examined the extractor and it looks fine. Unknown if the spring is strong enough or not though. The second possibility could be that the action is trying to pull the casing out before the pressure has went down (or the bullet has left the barrel)

Has anyone else experienced this problem?

I'm shooting a 300/221 M1S 16" barrel, CAR length AGT full open and with full size stock and buffer setup. Is there any signs that I can look for to indicate which it may be?

I'm going to replace the extractor spring 1st then if that doesn't work I'm going to be clueless.

I did notice that I could hear the bullet impact at 100yards and also on the recoil I could see the bullet right before it struck the target at 100yrds. That was funny. I was using the Corbons and single feeding them. I even let a friend watch it through the scope on a couple of rounds. It didn't leave oblong holes. The bullet was stabalizing. I don't have a Chrono, but I would say they are in the 850-1000fps range.

Anybody have any input I would appreciate some thoughts on this one

[rednek58]

I know two things that might help you with the failure to extract. D-Fender brand ring that fits around the extractor spring, also a heavy Wolff extractor should help. Either one alone might work, but I have used them together with good results. Hope this helps.

[sharpshooter33]

Ok, I've fixed my extractor problem. I now have a fully functional 300/221 fireball from Model 1! I'm using Jrippers load of AA1680 at 11.0gr and 220gr SMK's sized alittle longer than Corbon's, but they still fall below 2.260 OCL. I've used RP and LC cases and both are just fine. This load seems to be shooting somewhere around 950fps.

I'm a happy camper! Now I just have to get a suppressor and my project will be complete.

BTW when I put it back together I ordered a MRFS-C and drilled a hole for my AGT. It is a bad ass looking setup right now. Will be even nicer when I get it suppressed.

I see a 300/221 bolt gun in the future also. I'd like a real quiet one. 8-)

Thanks for all the input here guys. I would never known I had a problem unless I was reading these posts and I wouldn't have known how to fix it either.

Thanks
SS33

[jripper]

Glad to here your upper is running well. Mine is also, altough a few weeks ago, a friend came over, and we went to try it out, and I got failure to feed/extract short stroking again, sub sonic or super sonic. When I pulled ou t my bolt, I found that the carrier key had come loose. I then noticed that the "staking" on the model 1 bolt did not even touch the allen screws. I put red loc tite on them, and staked them a little deeper, and it all works again.

Just something to check if you are using a model 1.

Thanks everyone here for their help, as I don't think I could have gotten it going without the input here

Joel

[jripper]

I finally chronographed my 11.0 AA 1680 and 220 sierra load. Out of my 16" M1S ar, 3 shots averages 980, with a high of 1020 and a low of 933.

Only did three, as that was all I had on hand, and it was starting to rain.

Joel

[dlt223]

Hello All,
I chose to go with a PacNor Barrel Blank, finished by John Noveske.
He recommended a Port Diameter of .125" since that is the ID of the Gas Tube.
He also recommended the port at the Pistol position.
I chose to stay with the carbine position, since I am using the JP adjustable Gas Block.
This setup works well and I am able to tune for various Loads.
E-Ya Later, Dave

[Artful]

:confused: Hello new guy from Arizona trying to get information and make my mind up about how I want my upper for subsonic loads.

Some background I'm newish to AR's and have already decided on CAV15 lower (CAR spring & buffer in MarkII). I'm looking at the all information on this site (well still looking thru it) and think I have my wish list.

Flat top upper - Free Floating forearm - Pistol position AGT - Stainless 16 inch barrel 8 inch twist treaded for the ACC Cyclone I have coming. But based on what I see on this thread I wouldn't order Model 1 upper for anything.

I see how much trouble you guys seem to be having with Model 1 upper's with carbine position non-AGT and wonder if someone hasn't expressed to them that they need to offer the option of having the pistol position with adjustable gas system....? After all you guys talked to them didn't they say anything other than our well broken in test rifle ran perfectly with every load under creation. :eek:

I mean they need to wake up - you should have to tinker like that with a production product (drilling out ports :bangin: ) stuff like that is part of where the AR jamomatic stories started.

But just wondered as the new guy on the forum - it's nice to have found you all. :D

[d-mon]

I have read a lot of threads recently about people who had cycling problems with their AR uppers.
But would the problem had existed if the work had been done by serious guys who know about it like SSK industries?

Sorry, I just try to understand things here.
ND

[jripper]

I have no doubt that SSK make a better product, and that it would work right off the bat. However, if I remeber correctly, a .300 whisper SSK upper is around $1000 (upper only). I think I paid around $500 for a complete upper and lower parts kit.

For the extra $500 I save on a M1S, I don't mind tinkering a little to make it run.

If you have the extra cash, by all means, go with the SSK.

If not, and you aren't afraid to work on it a little, go with the M1S.

Just my thoughts,
Joel

[d-mon]

I did not know how much they charged. i understand now.

D-mon

[GMHA375]

To each his own.

Mine: SSK upper, SSK suppressor, corbon 220 subsonic ammo. Perfect flawless function from the first round. Worth every penny to not have to fiddle with it.

[AR15barrels]

For the extra $500 I save on a M1S, I don't mind tinkering a little to make it run.
Joel

I understand the logic when there is a $500 difference, but also realize that you are buying a $70 shaw barrel at the $500 price point.

$1000 is on the high side for a complete upper considering JD probably uses a $200 Shilen blank.

I can sell you a complete Shilen or Douglas barreled upper for about $750.
It will be custom made to your specs.
The throat will be perfectly centered in the bore, the gas port will be the right size and location (pistol) for both supersonic and subsonic loads.
I also take JP adjustable gas blocks and turn them down so that you can easily fit them under a freefloat tube.

You will not find any 7 page forum topics about getting my barrels to run right...

Randall Rausch
www.ar15barrels.com

[MMA10mm]

I too bought a Model 1 Sales 300/221 kit w/ assembled upper, and have had the same experiences.

I've read about the opened-up port in the standard shorty location, but that seems like a marginal fix to me. It will probably work with subsonic, and to get best success, use a chrome-plated AR-style (lighter-weight) bolt carrier, a lighter weight buffer spring, and don't plan on shortening the barrel any...

I want my lower to work with other uppers, without changing out the buffer spring, so that's out. I want to be able to utilize a heavier bolt carrier and shorter barrel, so now we're back to marginal operations...

In my opinion, if you're going through all the trouble to modify it, make it as close to the SSK upper as possible: TIG weld the gas port under the front sight, drill a new port at the pistol position (7-8" depending on whose gas tube you use), and for best operation, get an adjustable gas block.

This is more involved than just drilling out the port, but it will be the most flexible in terms of working with the widest selection of loads, and with the least amount of fiddling with the lower and bolt. Theoretically, these modifications should keep the 300 upper modular, as the whole AR system is meant to be, meaning you can swap out bolt/bolt carriers, and put the upper on different lowers with a high probability of it working...

Lastly, there have been some posts here in this thread which show the downfall of the JP gas block. (the allen wrench) To be fair, the JP block was designed for use on target guns at the match ranges, where mis-laying an allen wrench or leaving it at home will not get you killed. But, if you have a 300 for field use, I would think you'd want an adjustment device that is always attached. Again, I look back to the SSK upper, and note that they install a large knob with a coin slot that shows up through one of the holes in the upper handguard. I will be working on something that will work similarly with the JP gas block on mine...

My next problem to overcome is how to work the adjustment device around a solid 4-rail handguard without cutting holes through the Picatinny rails... When I get it all sorted out, I'll post some pictures here.

[Cornholio]

Sounds interesting! I need a fix for my gas block/tube set-up, so I'm eager to see how yours comes out!

[jripper]

I agree that moving the gas port to the pistol position would be the best way to go. I do not have a problem with my AA 1680 load with subsonics, with either a full butt stock, or car, using stock springs and bolt carrier. However, as previously noted, it will not work with faster powders. This is adequate for my uses. However, if you want it to function with any subsonic loads, you had probably better move the port.

Joel

[MMA10mm]

Well, before modification, Cor-Bon 220gr Subsonics won't work, but my handloads with 150gr FMJs and 17.5grs of W-680 (Surplus from Jeff Bartlett) worked just fine... Cycled every time!

Also was able to make hot loads with H-110 work, but they were about 1.0gr overload. (They were right at the suggested max load from SSK, and I was using more voluminous Rem. 221 brass vs. the re-formed mil. brass that SSK uses, but they were still hot...)

Anyway, at least I could get the thing to shoot semi-automatically before modification... I'll probably shoot it some more and then do the mods when the weather gets bad.

[TerroristHunter]

Just put together my M1S barrel on a CMMG upper with an Adams Arms Piston kit. Haven't tried the AA1680, but H110 and Reloader 7 haven't cycled yet. After drilling out my barrel to the same size as the gas block hole (.155) it will at least eject. I have also cut 1/4 off of the buffer spring (and stretched it out), and removed one of the weights from my buffer. The Adams Arms is a heavy Bolt carrier, but there is an option of just installing a key on a regular carrier. (Maybe chrome lightweight) Will keep you posted...

[TerroristHunter]

By the way, M1S will turn the barrel down to install a pistol position gas block, but it costs an extra $100.00

[mak91]

I got a m1s 300 whisper barrel back in 2004. Did the same thing, drilled out the port, cut the buffer spring, tried a bunch of different loads with Reloader7, Accurate 9, and Hodgdon335. Got some loads to cycle most of the time but never got 100% reliability. I also wanted to shoot some non subsonic loads some time and this setup would not work for the higher pressures. I finally figured out something to try, a double gas port configuration. I had tp555 make me a custom gas block. The adjustable gas block has 3 settings, off, pistol gas port and carbine gas port. In pistol gas port position the carbine port is blocked and gas only flows back to the bolt from the pistol port, same goes for the carbine port position, gas only flows from the carbine port to the bolt, the pistol port is blocked. This gives me the best of both worlds. Since I had already drilled out the carbine port to a larger size trying to get it to work in the original configuration I now have to use an adjustable gas tube to get the pressure right.

[Artful]

Pretty trick - what did that set you back?

[mak91]

I did all the work my self except for the gas block. For the block I had tp555 make me a prototype off the block he was already making. I am not sure what he would charge to do this work or for the block. IM or email him, real nice guy to work with......

[worksalot]

I will just throw this out...do with it as you please. I ordered my model 1 sales barrel a few months ago and did a lot of shooting getting ready for a hog hunt. Here is what I have found to work on my upper.Let me start by sayingit took about 50 rounds and a lot of lube to break every thing in, it was very tight to start with.I have the 16 inch barrel with the gas port in carbine location the port size is what ever it came from model 1 as. This is what works for me. h110 or n110 or win296 for super sonic loads from 110gr to 150gr all function fine no problems. Subsonics, I am using accurate 1680 with the standard carbine spring and buffer in my vltor stock. I tried using the n110,h110 and 296 for subs but they would not cycle unless i used the lightened buffer and special whisper spring that i ordered from model 1 when i ordered my barrel. I didn't want to switch buffers and springs to change from subs to supers so i found a powder that made the subsonics function in the supersonic configuration. I have seen a lot of negative stuff about the model 1 sales uppers but mine has been great. They need to be shot abit and lubed to break in but after that just work with your powders. It is asking alot of a semi auto to function with full house loads and then sub loads using the same powder because your pressures are way different. So give it a powder that has a slower curve to operate with the subs. just my 2 cents worth but i have put about 500rnds down range with my whisper in the last 2 1/2 months and love it...

[worksalot]

I will just throw this out...do with it as you please. I ordered my model 1 sales barrel a few months ago and did a lot of shooting getting ready for a hog hunt. Here is what I have found to work on my upper.Let me start by sayingit took about 50 rounds and a lot of lube to break every thing in, it was very tight to start with.I have the 16 inch barrel with the gas port in carbine location the port size is what ever it came from model 1 as. This is what works for me. h110 or n110 or win296 for super sonic loads from 110gr to 150gr all function fine no problems. Subsonics, I am using accurate 1680 with the standard carbine spring and buffer in my vltor stock. I tried using the n110,h110 and 296 for subs but they would not cycle unless i used the lightened buffer and special whisper spring that i ordered from model 1 when i ordered my barrel. I didn't want to switch buffers and springs to change from subs to supers so i found a powder that made the subsonics function in the supersonic configuration. I have seen a lot of negative stuff about the model 1 sales uppers but mine has been great. They need to be shot abit and lubed to break in but after that just work with your powders. It is asking alot of a semi auto to function with full house loads and then sub loads using the same powder because your pressures are way different. So give it a powder that has a slower curve to operate with the subs. just my 2 cents worth but i have put about 500rnds down range with my whisper in the last 2 1/2 months and love it...

[sten668]

Hey Worksalot, great news you have for me. I have just started shooting my MS1 config. I am hoping I can find a sub load for the 3000 175gn FMJs that I have. 1680 is on my list to try. H110 works fine with super sonic loads. What bullet/powder combo are you using? The dream would be to get my 225 cast loads to cycle while subsonic... they maybe will have to be bolt gun only fodder.
good shooting
Marv

[worksalot]

This load works in my rifle and is safe but each rifle is not the same and what is safe in mine may not be safe in yours.......now that i have that out of the way. I use 11gr 1680 under 208gr amax bullet 1000-1030 fps . They cycle mine and lock the bolt back on the last round. Hope that gives you something to work with.