Need some help with ar15 upper....

[azngunslngr11]

Need to know more info.

Who made the barrel (and other components)?
How did you check gas block alignment? (95%+ this is the problem) -> is the barrel dimpled?
Verifying a gas key is sealing is very difficult unless it obviously loose.
What size gas port? No, calipers will not suffice. You need a pin gauge set. (knowing who made the barrel would help possibly without needing a gauge pin set)
What brand of XM193?
How did you verify the gas rings were ok?

Also, absolutely no need to cut a buffer spring. Waste of a spring.

Short stroking is almost always a lack of gas issue -> very rare instance of a too small gas port (most make their slut sized ports to cycle cheap ammo without complaints), gas port obstructed from a manufacturer possibly drilling the port after CL, gas block not drilled for a gas port (airsoft, and yes I have seen people use these), carrier key not drilled for a gas passage (yes, Anderson has let some of these slip out the door), leaking gas key (did you check the fasteners were tight?), gas tube installed upside down (yep, seen that one way too many times now), blown primer in carrier key (yes, it literally can happen), incorrectly manufactured buffer spring, severely worn gas rings, gas tube installed in front of the roll pin (yes, I know, but people can screw up a bowling ball in a sandbox), carrier expansion chamber too tight from improper machining or CL and the bolt binds inside the carrier, Gas tube worn and the flared bell no longer seals in the gas key, gas vents in carrier missing (Radical with their finest QC controls), etc...

 

[freedom]

Did you dimple the barrel? Faxon doesn't dimple for you, you'd need to do it yourself.

How did you line up the GB? Another reason to dimple with a jig is it ensures proper alignment without eyeballing coming into play.

Is it a Faxon GB? Theirs ship with cup tip screws which aren't the best option for a secure install.

Faxon gas ports aren't huge, but they are larger than crane spec. Port size isn't the issue.

 

[azngunslngr11]

Who made the barrel (and other components)?- Barrel Faxon Firearms, gas Block Midwest Industries, gas tube is generic, upper made by X-Products, Bolt/BCG ,ade by Aero Precision
How did you check gas block alignment? (95%+ this is the problem) -> is the barrel dimpled?
- Bottom of barrel is dimpled for gas block seating. Dimple aligns with gas port on top side of barrel, Removed set screw and check alignment. set front screw to make sure it did not rotate, and then set rear set screw into dimple. carbon build up on gas block and top of gas port show gasses are being directed into block.
Verifying a gas key is sealing is very difficult unless it obviously loose.
-Sprayed WD40 into Gas Key, and blew air into key, looking for bubbles.
What size gas port? No, calipers will not suffice. You need a pin gauge set. (knowing who made the barrel would help possibly without needing a gauge pin set)
- Still need to do.
What brand of XM193?
- Lake City
How did you verify the gas rings were ok?
- Gas ring tested (not scientific) by bringing bolt forward position from the BCG and standing the bolt face without the bolt collapsing back into the BCG.

Thanks for your help!

 

[Plinker66]

I fussed with a blackout pistol barrel with a carbine length gas/short dwell time system fer a while and never could get it running smooth.

Drilling can leave a burr

I would dump the barrel for a barrel with a pistol length gas system.

IMO 2” of dwell time ain’t never gonna run smooth.

 

[azngunslngr11]

Sorry Guys, the barrel is:
AR-Stoner Barrel AR-15 Pistol 5.56x45mm NATO Medium Contour 1 in 7" Twist 10.5" Chrome Moly Melonite- Purchased from Midway.
From what I see these are made by Liberty/Satern

 

[freedom]

It does work perfectly with other uppers?

 

[azngunslngr11]

I fussed with a blackout barrel with a carbine length gas/short dwell time system fer a while and never could get it running smooth.

Drilling can leave a burr

I would dump the barrel for a barrel with a pistol length gas system.

IMO 2” of dwell time ain’t never gonna run smooth.

Would doing a short stroke piston conversion system help? Looking at replacing the gas system with an Adam Arms Piston conversion.

 

[azngunslngr11]

It does work perfectly with other uppers?

Works fine with 14.5" and 16". But its prefers when i run a heavier H2 buffer instead of the H1. Where as the 10.5" won't even cycle with H1 or H2, and runs...ish.. reliably with a carbine standard weight of 3.0 oz. with Lake City X193 5.56

 

[freedom]

That's a bottom barrel barrel.

 

[Plinker66]

I have zero experience w gas pistons.