Hi, all!
I got a RRA NM rifle still new w/ about 200 rounds through it. When I was going over the rifle, I noticed that bolt carrier is shaving some portion of upper receiver's interior wall. Even though I only shoot 200, I do lot of dry fire practice for aiming & position.
A picture could tell the whole story much faster but let me see if I can explain.
On upper receiver's interiror wall, if you see through the ejection port (on the opposite side), there is a small vertical cylinderically machined portion in interior wall where bolt carrior moves back and forth. Due to the vertical clyinderical machining, there is a discontinue of interior wall. Since bolt carrier's overall diameter is small than upper receiver's internal wall, I guess bolt carrier could be cockeyed while moving & catch that discontinued portion of inteiror wall created by vertical clyinderical machining.
Bolt carrier has 4 smooth rails machined that slide against upper receiver's interior clyinderical wall. It seems that bolt carrier's upper left rail (while holding rifle as you would shoot) leading edge is catching the disconnected interior wall of upper receiver. Bolt carrier's rail machining seems perfectly fine and I could smooth out the rail's leading edge w/ Dremel.
I'm sorry for this long & wordy explanation but should I be worried about interior wall being shaved by bolt carrier? Is this normal break-in? I still see the shaving is happening and interior wall's black finish is shaved away and shaved portion is getting bigger.
Thanks,
Matt.