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View Full Version : Yet another fascinating gas question for the guru's.



Joelski
4 November 2018, 14:38
So I installed an adjustable gas block (Insert crow pie jokes here). I started off 2.5 turns out and it locks back on a single round. Next try, same setting, no lockback. I am not giving up, added a little more lube and put two rounds into the mag, fired and the second round jammed only partially into the chamber. I drop the mag and pull the CH and the round drops into the chamber easily (Telling me it's not damaged, or at least not terribly). No dice; I clear that round and it shows evidence of swiping at the base of the case, just above the chamfer of the case head. I can add a pic if desired, I didn't see that round on a cursory look through my bag.

So question; is this what "Short stroking" is, and is it a condition of too much, or too little gas? It seems I need a half turn more on the GB to get the bolt to lock back consistently, but is it also the reason for the misfeed? I am using standard AR 308 carbine extension with stock spring and buffer (All matching Aero Precision parts to go with the rest of the gun) I figured sticking with this one manufacturer would eliminate effed-upness of AR 308 rifle gas system finnickery. Am I on the right trail? I ask because I've had fantastic luck in the old "If it works, do not fuck with it" school of thought as it applies to shooting sports and life in general.

P.S.: I was not making a bunch of shots on the same setting for no reason; I was honestly looking for repeatability of success of failure, knowing other things like newness and lube can add to the problem.

Stone
4 November 2018, 15:28
This guy nails it. Listen for the loctite tip at the beginning so its not moving on you as well. I am thinking 2.5 turns was too much. Start at one full turn...
https://www.youtube.com/watch?v=voJnsA2B7UY

BoilerUp
4 November 2018, 18:44
What ammo? I had something similar happen on a different rifle today and I believe it was because the rounds were slightly higher pressure and therefore the system was a touch over gassed. Also, I was running pretty dry as I forgot to bring oil to the range. If you've got swiping, you might need to close the AGB a touch more. Short stroking is the opposite - not enough gas to bring the bolt back far enough to pick up the next round.

Joelski
4 November 2018, 21:04
What ammo? I had something similar happen on a different rifle today and I believe it was because the rounds were slightly higher pressure and therefore the system was a touch over gassed. Also, I was running pretty dry as I forgot to bring oil to the range. If you've got swiping, you might need to close the AGB a touch more. Short stroking is the opposite - not enough gas to bring the bolt back far enough to pick up the next round.I'm using Lake City 7.62 ball, so it could be a pressure thing...

Stone, I'm not losing my setting, just wondering my next step.

mustangfreek
5 November 2018, 00:04
Maybe a mag problem? Did you try another magazine

I don’t have a ar10 but that ammo should be fine, buffer setup sounds correct

I’d do a once over, lube it up and go back out and play with the settings, and run some more ammo thru it

BoilerUp
5 November 2018, 06:44
I'm using Lake City 7.62 ball, so it could be a pressure thing...

Stone, I'm not losing my setting, just wondering my next step.

That ammo is actually pretty wimpy, so I suspect you just need to break in the weapon. Re-reading your OP, yeah, you might want to open up the AGB a touch more. You should probably be close to full open for that ammo. I'd suggest you run some commercial .308 through it. I had some feeding issues with milsurp early on and most of them went away when I switched to .308 ammo. Since I have a precision barrel on mine, I almost exclusively run .308 anyway but I'd half expect my setup to be tuned to be under gassed for LC 7.62.

Joelski
5 November 2018, 12:34
I am not running a can on this, BTW.

JMJ
10 November 2018, 19:09
Get her running right?

Joelski
10 November 2018, 19:18
Hoping to make it out tomorrow. I'm thinking a half turn out should have it sorted.

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