QUOTE: Here is what do know, the bolt is not overiding. It is firmly pushing back of the case. Pushing the forward assist sends the round into the chamber, bolt into battery, and the rifle fires. The rifle runs fine after the first round is in. This is only happening on the first round. Not a mag issue. Unless 11 magazines ranging from new commercial, new GI, to very well used GI who went through both Iraq and Afghanistan all have the same flaw. No mag with slow manual cycle creates no hang ups. Manual cycling doesn't feel as smooth as used guns.
If it were bad lips, bore, assembly, the rifle would stop during firing. This isn't the case. Gun cycles 100% under recoil.
It seems there is too much drag for inertia to overcome or the spring isn't providing enough force to counter the drag of the bolt and magazine together.
I think it is one of two things, or both. Poor polish/over coating of bolt carrier or weak recoil spring. If spring, a wolfe extra power spring should do the trick but I worry short stroking. If rough finish, gut should break it but I also wonder about helping that along.
I see no reason to ditch a rifle that otherwise works as intended. Logic and mechanics will sort it out. Why take the easy road?[/QUOTE]
I had one kit build that had an out-of-spec upper receiver. The bore that the bolt carrier slides in was axially misaligned to one side--the bolt carrier did not slide straight along the centerline of the buffer tube. Once it was firing it was OK because the action was violent enough make the gun function. When hand cycling the bolt carrier would wedge itself against the inside of the buffer tube and stick in the rearward position. "Reverse-mortaring" the gun by driving the muzzle down onto a block of wood was enough to dislodge it and the bolt would slam into battery. Replacing the upper after finally figuring out what was wrong made it function correctly.
I'm NOT saying your upper is bad, I'm saying the possibility exists that the carrier may be encountering drag/resistance inside the buffer tube. You can check it by removing the buffer and spring and re-assembling the gun with JUST THE CARRIER. (no bolt) Tilt the muzzle skyward and back down and the bolt carrier should slide easily back and forth without resistance.
I know it sounds crazy but what have you got to lose?
If it were bad lips, bore, assembly, the rifle would stop during firing. This isn't the case. Gun cycles 100% under recoil.
It seems there is too much drag for inertia to overcome or the spring isn't providing enough force to counter the drag of the bolt and magazine together.
I think it is one of two things, or both. Poor polish/over coating of bolt carrier or weak recoil spring. If spring, a wolfe extra power spring should do the trick but I worry short stroking. If rough finish, gut should break it but I also wonder about helping that along.
I see no reason to ditch a rifle that otherwise works as intended. Logic and mechanics will sort it out. Why take the easy road?[/QUOTE]
I had one kit build that had an out-of-spec upper receiver. The bore that the bolt carrier slides in was axially misaligned to one side--the bolt carrier did not slide straight along the centerline of the buffer tube. Once it was firing it was OK because the action was violent enough make the gun function. When hand cycling the bolt carrier would wedge itself against the inside of the buffer tube and stick in the rearward position. "Reverse-mortaring" the gun by driving the muzzle down onto a block of wood was enough to dislodge it and the bolt would slam into battery. Replacing the upper after finally figuring out what was wrong made it function correctly.
I'm NOT saying your upper is bad, I'm saying the possibility exists that the carrier may be encountering drag/resistance inside the buffer tube. You can check it by removing the buffer and spring and re-assembling the gun with JUST THE CARRIER. (no bolt) Tilt the muzzle skyward and back down and the bolt carrier should slide easily back and forth without resistance.
I know it sounds crazy but what have you got to lose?
