All,
Took my 6.8mm AR to the range for some trigger time a couple weekends ago. I fired about 9 rounds to get it sighted in and then started taking shots at a target downrange. After I'd fired about 15 total rounds the rifle stopped cycling properly. With a round chambered and about 5 left in the mag, I pulled the trigger and got a bang, but the rifle wouldn't go back to safe because the hammer wasn't cocked. The BCG was slightly out of battery and it wouldn't move when I pulled on the charging handle. I dropped the magazine and tried to clear the chamber. I had to pull extra hard on the CH for the BCG to come loose, and the empty brass then ejected out the port.
I re-inserted the magazine, now with about four rounds left, and tried again. Same result; the rifle went bang but the BCG budged only a little and the spent brass remained in the chamber. Again, with a little elbow grease I was able to eject the spent brass and chamber a new round. I repeated this until the mag was empty.
Up till now I'd been firing Remington 115gr Matchking ammo. I reached into my range bag and pulled out some Hornady 110gr VMAX and loaded 5 rounds into the mag to see if it would behave any differently. I fired 4 rounds with the exact same result. No unlocking, only a slight movement from the bolt carrier. My AR had effectively become a single-shot rifle.
I field-stripped it and could not find anything unusual about the BCG or any of the parts. None of the brass I recovered looked abnormal either.
Here are the specs of my rifle:
AR15 Performance Recon Upper 16"
Stag forged lower
DPMS LPK
H2 Buffer
Tactical Springs extra power "red" buffer spring
C-Products 25rd magazine
The AR was well-lubed throughout. I've had this lower for two years, and I've been running this upper on it for almost a year now. Trigger time is scarce for me these days, but of the half-dozen or so times I've had this upper/lower combination out to the range it has never malfunctioned like this before.
Pictures:
http://i596.photobucket.com/albums/t...7-23130858.jpg
Bolt carrier group
http://i596.photobucket.com/albums/t...7-23130409.jpg
http://i596.photobucket.com/albums/t...7-23130327.jpg
http://i596.photobucket.com/albums/t...7-23130259.jpg
Don't know if those pics are helpful, but there they are. So does anyone know how to address the problem? Thanks in advance.

