Issued this ammo for duty use.

I recently got a 10.5 upper from MICRO MOA with the Govnah installed. The upper works fine with 5.56 ammo on a .073 gas port. Ive been trying to make it run with our duty ammo and having issues. I was using a  standard carbine spring and carbine buffer. The BCG would lock back on one round mags for about 7-8 mags on the .073 setting with the Winchester ammo. Then it stopped locking back.

I swapped over to a .078 setting and ran several more one round mags through it without issue using the Winchester ammo. I then did one or two 15 round mags and got lock back every time. I tried a few more one round mags and the BCG stopped locking back. I get lock back every time on the .078 using cheap .223 American Eagle ammo but the Winchester Ranger wont.

Ive tried ammo from different lot numbers. Same issues. Ive ruled out the upper malfunctioning for now. Ive tried different spring strengths and buffer weights and have the same problems.

Can this ammo be that under powered? Has any one done any testing on it? I dont have access to a Cronograph.

I dont have any issues running it in my 10.3 DD or 10.5 PSA even with a xtra stiff spring and H3 buffer. Both of these uppers are very over gassed though.

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