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