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Discussion Starter · #1 ·
Hoping for thoughts on common AR questions..."over or undergassed?"..."too light or too heavy buffer?".

Just added a can to my DPMS Gen 2 308. Anticipated increased back pressure so added an adjustable gas block. Also added a heavier Odinworks adjustable buffer. Getting FTF issues as shown below.
1. Rounds feed fine from locked back bolt.
2. Subsequent rounds ftf with bolt hitting shoulder. This happens with 147gr mil surp ammo and 168gr match loads. Also happens with different mags.

I need to experiment but would like thoughts on where to start.
3. One theory...bolt is moving too fast for mag to present cartridge rim. Therefore, add weight to buffer or decrease gas?
4. Or is bolt not moving far enough rearward to catch the end of the cartridge? Therefore, lighten buffer or increase gas? Slide does lock to rear after hand feeding a cartridge.

Thanks for any help with this!


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The Shadow (Moderator)
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Kinda need to know if it's short-stroking, or the magazine isn't pushing things up quickly enough.
Adding parts to "fix" a potential problem, before it materializes can be an unending trip down the rabbit hole sometimes.

I would put it back to stock, and see what happens.

Cheers
 
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Discussion Starter · #3 ·
Good recommendation.

Odinworks has responded to my question. Their first thought was "overgassed". Recommended dialing back gas and the increasing buffer weight.
If I had the right gear at the range the other day, I could have tried a few of these adjustments. Next week will start without the can and see how it runs. Then adjust gas down., etc.
 

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loading and shooting one round at a time, and seeing if the bolt locks open on an empty mag can tell you if the carrier is making the trip all the way to the rear. though sometimes an overgassed gun will cycle too fast for the magazine spring to push the bolt catch up. A little finger pressure on the latch will make sure it comes up. If it doesn't lock open on an empty mag, and if it doesn't lock open with a little finger pressure, the bolt carrier isn't making the trip, which probably equals undergassed.
Are you confident of the gas tube alignment with the port when you added the adjustable gas block?
your idea of trying without the can is good. You added two variables - can and gas block - and testing them one at a time will help you isolate the problem.
 

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The DPMS AR10 mags can be finicky have you tried a different brand mag? If I remember correctly Magpull mags aren't recommended for the Gen 2 but they have fed 100% on mine.
 

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Discussion Starter · #6 ·
The Magpul issue with DPMS gen 2's is for real.
Learned this the hardway wasting many rounds trying to tune the rifle to get the magpul mag to lock back.
Turns out that on some magpul mags the follower will not rise high enough for the bolt to catch and lock back. Dremeling a bit of follower off the right side where it contacts the feed lip allows the follower to rise to the proper height.
 

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one addition to my earlier post: if it doesn't lock open on an empty mag, but does lock open with a little finger pressure on the bolt catch latch, then the carrier speed may be too fast, and you're looking at overgassed. Hope that helps. Let us know what you find.out.
 

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Discussion Starter · #9 ·
Thanks for the ideas. Hope to get up to range this coming week.
Got to the range today. Testing confirmed rifle, like owner, was overgassed with supressor.
I increased buffer weight and dialed gas back.

Milsurp and target loads now feed fine and eject to 3 o'clock. Bolt locks back when it should.

Only issue now is the dang charging handle pops loose.

Thanks for all your comments and suggestions.
 
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