Help with SBR AR functioning

[Ga.Dawg]

Need some help with malfunctions
Noveske gen 1 upper and lower
Noveske nitride bcg
Noveske 12.5” 300bo barrel cut and threaded to 11” and assembled.
Geissele H2 buffer & spring(also used a H1)
Geissele SSA-E trigger
LMT internals and buffer tube assembly
Mags consisted of four Lancer and one Magpul 300bo mag.
Rifle lubed up, 25 rounds of reloaded 220grn in each of the mags no can.
Four rounds then failure to feed, two rounds failure to feed, bolt not locking back on the last shot with all mags. Switched to H1 buffer and basically the same result. Added can and the same results using same mags and both buffers. The most rounds I got it shoot was five consecutive in total 100 rounds shot and no problems ejecting when it would run, this upper was sent off to a reputable machine shop for the work.
Thoughts on problems and solutions?
Thanks in advance.

 

[gyppo]

Sounds undergassed witte minimal information. If gas block is in proper position try more powder if you are not at max load.

 

[CTS Tactical]

By shortening the barrel you have reduced dwell time even if slightly. You will need to drill out the gas port if you want to fix it properly to allow for more gas. Generally take a wire bits set and find the bit that fits your gas port then open it up to the next size and try it. If not enough, go another size larger. I have never shortened an AR barrel where I did not need to open up the gas port.
Going to the H buffer is going backwards. If anything you want lighter reciprocating mass due to insufficient gas pressure. You might go with a semi auto style carrier with standard weight buffer and get it to function fine.

 

[BigMike]

Switch to full power ammo or a suppressor and repeat the test.

 

[lostchild]

I’d try it with a standard spring in place of the Geissele.

 

[Ga.Dawg]

Switch to full power ammo or a suppressor and repeat the test.

Shot it with my can same results.

 

[LongNose]

Sounds undergassed and short stroking, or too strong of spring

 

[steviesterno]

If it feeds when you charge it I would also think undergassed.

add can or try supers.

are the reloads known to cycle other guns?

 

[Ga.Dawg]

By shortening the barrel you have reduced dwell time even if slightly. You will need to drill out the gas port if you want to fix it properly to allow for more gas. Generally take a wire bits set and find the bit that fits your gas port then open it up to the next size and try it. If not enough, go another size larger. I have never shortened an AR barrel where I did not need to open up the gas port.
Going to the H buffer is going backwards. If anything you want lighter reciprocating mass due to insufficient gas pressure. You might go with a semi auto style carrier with standard weight buffer and get it to function fine.

I understand the buffer, I was trying to maybe find cause and a fix, do you think the inch and a half taken off would cause it not to lock back or cause the failure to feed due to the gas port size?

 

[Ga.Dawg]

If it feeds when you charge it I would also think undergassed.

add can or try supers.

are the reloads known to cycle other guns?

Yes the reloads are cycling other guns and the same results when I added the can.