Spike's 6" upper, ramped bolt, Wolfe XP spring, on a Spike's pistol lower with a CMMG 2 stage trigger and a CP mag block.
After the first round is fired the bolt chambers another round but will not cock the hammer. I switched the upper to a Spike's lower, RRA block, same spring and buffer only with a White Oak modified RRA 2 stage trigger and it ran great.
To confuse things more, I also have a RRA 16" upper on a Spike's lower, CMMG 2 stage with a standard .223 spring and buffer and a RRA block. It It runs without a hitch.
I even switched out bolts between guns and the pistol upper wouldn't run with either bolt.... My question is, what's up with the pistol configuration?? Any suggestions would be appreciated.
Oh yea, the floppy CP mag block seemed to work fine, although I didn't try to fire from any odd angles.
Does it run with a 223 upper?