I was helping a friend install a RRA lower parts kit in a stripped RRA lower a while back, and ran into an issue.

The selector simply would not fit into the hole in the receiver.  It was larger in diameter than the hole in either side of the lower.

The selector measured 0.375" and the hole was (IIRC) 0.370".  So was the selector too big, or the hole too small?

I did find a way to "make it fit" with a hammer, a 3/8" drill bit, and some polishing compound -- I didn't mar his lower *too* bad :^)

Just curious if anyone else had experienced this.  I've heard RRA lowers are "tight", but I see no reason why anyone would make them so tight that the selector won't go in, much less rotate.

Sounds like the hole was missed in the reaming process, not a common occurance.

Too late now, but he should have returned the lower. By drilling the hole, you've removed the anodization and now have the steel of the safety rubbing against raw aluminum. If he uses it a lot, the hole will elongate over time.

I bought one of those RRA selector levers and yes, they are too big.  Mine wouldn't fit in two bushmasters and one RRA.

The spec calls for the selector hole to be .376-.377", so it is definately undersized. The selector is supposed to be no larger than .375", so your RRA selector is correct. It is the lower that was the problem.