I have had this issue for the last 6 months where I am having primers pop and sometimes they get hung up in the barrel extension and jam the gun.  The barrel is a CMMG 1:7" chrome lined.  I have shot it with a standard spring and buffer, a standard spring and a tungsten buffer, a CS spring and Enidine Hydraulic buffer.  It will do it with any of the above.  I have a "D" ring on the extractor.

The ammo is XM193PD in the bulk pakaging.

Anyone have any ideas?

Quoted: The ammo is XM193PD in the bulk pakaging. Anyone have any ideas?

try different ammo!!!

xm193pd is known to suck... try something else...

PD ammo is problematic and from what I understand they are factory seconds or ammo that didn't pass inspection for whatever reason.

If you try another brand of ammo you will most likely solve your problem.

i have had the same issue with winchester white box.  it happened during training relay and once at the range.  

Quoted: PD ammo is problematic and from what I understand they are factory seconds thirds or ammo that didn't pass inspection for whatever reason.