Failure to lock bolt!!!

[terrywick4]

I'm telling you I had this same issue and I hooked up an air line to the gas tube in the receiver and was able to blow air thru it. I then moved the gas block forward and back and side to side till I was able to get the best air flow thru the gas block and all my problems went away.

[martkin64]

I'm telling you I had this same issue and I hooked up an air line to the gas tube in the receiver and was able to blow air thru it. I then moved the gas block forward and back and side to side till I was able to get the best air flow thru the gas block and all my problems went away.

I will give that a shot... I am going out tomorrow and see if my modifications work... Thanx guyss I will keep you posted

[LRRPF52]

What gas system length do you have? If it's a Rifle-Length gas, then .099" might be just enough. I know some guys with 18" RLGS use a port diameter over .100", because of dwell time and bore volume.

If there is any inefficiency in the gas system, like a lot of leakage from the gas block, then that is gas that isn't staying inside the circuit, which reduces gas pressure inside the carrier and bolt tail chamber, and you can often end up with failure to lock on last round.

Also, as several have mentioned, the addition of after-market bolt hold open devices with a protruding lever into the trigger guard will often prevent normal operation of the bolt catch. We noticed this yesterday in one of my AR15 courses.

I personally measure gas port locations with calipers on the barrel and block, so that we get perfectly concentric alignment, then seal the gas block and gas tube.

[martkin64]

Ok I finally got back out and was able to shoot. I used a 25 rnd mag and it locked back every time. My 10 rnd mag still failed to lock back. . The funny thing about it was,my buddy was able to use my 10 rnd in his Grendel AR and it worked every time for him..
But if thats what it will take Im going to buy a 25 ruond... Oh ya, the 25 rnd mag was a C product defencs mag and the 10 rnd is an AR Stoner.

[arnie]

Stretch the mag spring in the stoner .

[martkin64]

Stretch the mag spring in the stoner .

I will give that a try... Thanks

[LRRPF52]

Stretch the mag spring in the stoner .

I would consider not doing this. The springs are set with a temper, and bending them after that doesn't really help. Something else may be going on with the mag.