While fitting parts into my RRA Lower Receivers, I noticed that the "nipple" pin that locks in the selector lever does not fit properly.  It seems that the hole, which is located under the pistol grip, where the pin and spring fits into is too small for this part.  I ran into this problem on all 4 of my RRA receiver, which were purchased over a 3 year period.

I believe that the lower parts kit I'm using is either from DPMS or STAG.  I have several other brands of lower receivers and this isn't a problem... Any tips in correcting this??  

I ready don't want to force the pin all the way in since I fear getting it lodge in too tightly where I'm not able to get it out or it will lock-up the selector lever.

Does anybody know if I will have to use a locking/nipple pin made by RRA or if I have to file out the area a little...  If so, with what??

Thanks for looking!!

just a tip, work with the cheapest, most easily replaceable part.  I would modify the detent before I would modify my receiver. YMMV

I'll bet the detent pin isn't very much larger than the hole. I'd roll it around in some aluminum oxide sandpaper to see if I could reduce the diameter a hair before messing with the lower! If this doesn't work, just buy a few detent pins from brownells.