AR not locking back even when suppressed.

[.Scarecrow.]

My AR will not lock back on last shot with a new buffer spring I put in. It's a Sprinco standard "White" spring that is suppose to be like a fresh carbine buffer spring. I'm running an H-buffer, a Sionics Barrel with something close to a .075" gas port and a VLTOR clamp on gas block. I did notice a lot of carbon fowling that came from my gas tube roll pin spraying out onto the inside of my handguard when I was shooting with my Griffin Recce 5 Suppressor, and actually caked up a good bit of residue there. Should I just run a CAR buffer or is my gas block leaking too much?

Thanks guys.

 

[badkarmamib]

What magazines are you using? Will it lock back if you manually, quickly cycle the bolt with your magazines? Does your bolt hold-open latch move without any binding?

 

[carbine85]

Is your gas block liner up correctly. The H buffer shouldn't be a problem but you might try the standard buffer.
Make sure your receiver extension is tight and check the gas key on the bolt carrier.

 

[readyeddy]

Try replacing the spring with either the old spring (if the gun had one), or get a stock spring.

 

[LoonWulf]

What loads u running?

Heres the order id check stuff.

Gas block, check alignment front and back aswell as side to side, and tightness.
Gas tube, when the blocks off look and make sure your gas tubes hole is lined up with the blocks, and that there isnt alot of excess play in the tubes fit.

Carrier Key, and gas rings.

Buffer

Buffer spring.

 

[agtman]

Sionics barrel, with a mixmaster of other parts? Vltor's and what-nots?

Hard to tell.

 

[.Scarecrow.]

I'm running Pmags, shooting XM193, and the gas block is good to go. Do gas blocks leak a little no matter what?

 

[LoonWulf]

To a degree most probably do, none of mine have been noticeable tho.

 

[carbine85]

It's fairly easy to check the gas block and port. Plug the chamber with a spent round and blow into the muzzle. The air should pass through the gas tube easily. I check my AK builds like that to make sure the gas blocks are lined up.

 

[C-grunt]

Leaking gas block is most likely your problem. Especially if it's enough to immediately notice.

Are you sure you have the correct sized gas block? Is the set screw in the barrel dimple correctly? Is the set screw secured with loctite or similar?

 

[.Scarecrow.]

It's a VLTOR Clamp on type, and yeah it's a .750. I noticed that when sliding it on, pretty tight fit.

 

[LoonWulf]

If your gas blocks tight and your getting leakage id guess you have an obstruction or improperly lined up gas tube port or ports.... Did you try the blow thru test

 

[HankC]

It's fairly easy to check the gas block and port. Plug the chamber with a spent round and blow into the muzzle. The air should pass through the gas tube easily. I check my AK builds like that to make sure the gas blocks are lined up.

Another way of doing it is using a 1/4" ice maker water line plastics tube to blow air into the gas tube end.