AR 15 300 Whisper Not Cycling/Ejecting

[milehipo]

Hello I have a new build(SSK)
AR 15 300 Whisper Matchgrade Upper - Barrel length 10"
AAC Cyclone Suppressor
RRA Lower Receiver Lar-15
20 Rd P Mags
Load:
9.1 H110
220 SMKHP
COAL 2.235
Gas block set for subsonic

Took Out this morning for the first time this morning and first mag cycled fine and ejected and fed round ok
2ND mag had cycling and ejection issues, no stuck rounds in barrel however half way ejected and fed.
Groups were ok for first shooting 2"-3"
Thanks in advance for help

[alorton]

If the first mag cycled fine my first thought is that the gas block or the carrier key came loose. If they weren't secured well they could vibrate loose in the first few shots and lose seal, bleeding off gas pressure. I would start there.

Is the gas block pinned or held on with set screws? Is the carrier key staked properly? Is the gas tube aligned with the carrier key properly?

That's where I would start.

ETA: How did you develop that load? It may just be too light to reliably cycle your gun when it starts to get a little dirty. Do you know the velocity you are getting? Have you tried any other powders?

[i8asquirrel]

I was having same type issue , I went to a slowwer powder (4227 & 1680) then lightened Buffer... Problem solved....Good luck

[milehipo]

I want to thank all for the help and different posts. As stated I was using PMags. I took one apart and used my dremel to trim specified areas. The rifle cycles properly and loads and ejexts rounds as it should.
Now my issues are with groups. As stated earilier I am using 9.1 gr. of H110. Groups are 3-4 inches at best. Tried 9.6 of same powder and groups did not improve much.
Is it that I need to allow the barrel to break in?
All components are tight(Optics, suppressor).
Thanks for the help.

[i8asquirrel]

Originally Posted by milehipo

I want to thank all for the help and different posts. As stated I was using PMags. I took one apart and used my dremel to trim specified areas. The rifle cycles properly and loads and ejexts rounds as it should.
Now my issues are with groups. As stated earilier I am using 9.1 gr. of H110. Groups are 3-4 inches at best. Tried 9.6 of same powder and groups did not improve much.
Is it that I need to allow the barrel to break in?
All components are tight(Optics, suppressor).
Thanks for the help.

I would try A1680... I am using 11.5 gr over a CCI 400 primer pushing a 180gr Hornady BTSP and getting 3/4 to 1 MOA.. I had been having the same sort of problems and one of the folks hear helped with other powder suggestion..it really helped....good luck

[Rancid Coolaid]

I've had vertical stringing problems with H110 (spent months working on the gun and the setup, only to find it was the powder.)

Switch powders. I like #9 and lil gun, solves the problems for me.