My cousin just got an AR Stoner mpi bcg. We put it into his new PSA AR and fired 120 rounds through it just to pop it's "cherry". After taking it apart and cleaning it I noticed some marring on the bolt locking lugs. Is this normal? I have never seen it before on any other ARs before. Is this going to be a problem? Any advice is appreciated.
Does the Stoner bolt lugs have the KAC proprietary rounded design? If so it's not made to work with a standard barrel extension.
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together.
US Army 1966-69, VFW Life Member, Retired Geek