Quarterbore's Forums - Model 1 Sales 300 whisper upper function problems

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QuarterBore Wrote :

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

http://www.model1sales.com/item-deta...16carpost3.gif

Which configuration did you go with?

300Whisper_newbie Wrote :

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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

Abyssdncr Wrote :

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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

Jripper Wrote :

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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.

Jripper Wrote :

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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

Jripper Wrote :

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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

QuarterBore Wrote :

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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

Jripper Wrote :

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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 Wrote :

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

--Chris

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.