Originally Posted by
Skintop911
Range day this morning.
After restaking the carrier keys with a P-MOACKS a new problem emerged. Following insertion, the carrier met substantial resistance at the point the key screws entered the receiver. A quick check of the receiver and carrier finds nothing abnormal. Same result upon reinsertion. This time, I forced the carrier forward and found the same resistance throughout carrier travel into battery. Removed, repeated. Signs of friction were then found in the upper corresponding with the sides of the carrier key base.
I double checked the carrier key. Straight and true. No excess material displaced. No apparent issue.
Time for a parts swap. BCGs from 2 Colts, 2 Bushmasters, and 1 DPMS were available. The problem BCG inserts easily and travels smoothly in all other guns. The BCGs from those guns insert easily and travel smoothly in the RRA, but with less play. Aha.
I found a file on my multi-tool and cleaned up the sides of the key, and voila.
Diagnosis: Stacking tolerances between the receiver and the minimal material displacement caused by the restaking.
Noteworthy: The 2 BM and DPMS carrier had been done with the same P-MOACKS in identical fashion. Almost two dozen others haven’t produced the same issue, either.
Thereafter, the RRA fired a few hundred rounds of exercises and COFs without issue.