Originally Posted by
Boomer10
I know this is an old post, but I'm having similar problems with a new upper. I recently purchased an AR57 upper and put it on my Bushmaster lower (with a single stage trigger) that I've had for about 8 years (without any major issues). I took it to the range to zero it and it would load fine, eject fine, but after the first shot it would strip a round out of the magazine and seat it in the chamber, but it would not reset the trigger. I contacted the manufacturer and they suggested I try another lower and a standard buffer (the AR57 uses a proprietary buffer). I then tried the upper on my LMT lower (with 2 stage trigger) with the same results, first shot goes bang and is ejected, second round is chambered, but no trigger reset. After this I sent the upper back to AR57 so they could look at it. They test fired about 200 rounds on 4 different lowers and it worked flawlessly every time. At this point everyone involved is extremely baffled, anyone here have any thoughts?!?
Mods, if you feel this deserves it's own thread feel free to move it.