Great forum,  very interesting posts.  Saw an older archive posts about a mis-aligned selector detent hole,  could not post on that so new thread.   Guy wanted to plug the bad hole and bore a new one,  all kinds of responses on wether that would work or not.  I have a similar issue,  got a little too thin on my right side of Lower and detent pins falls out inside the lower.  Wondering what the thoughts here are on just drilling a new hole for the detent on the left side,  including the grip,  and using an ambidextrous safety selector installed backwards?    I have all the specs for the hole and it's a polymer lower so I don't see this as being extremely difficult.   Any reason this would be likely to not work ?  Thanks in advance.   Danny K.

If you flipped to the opposite side, it would also work in the opposite direction.  Appearing to be in FA when in safe.  

If it were me and an aluminum lower, I'd drill out the detent hole, thread it something like 1/2-28, loctite a screw in there, then drill the screw to hold the detent.  But that takes a lot of patience with a hand held drill or crappy drill press.  Since it's a poly lower, maybe just fill it with jb weld then re-drill it.

Since it's plastic, JB weld or plastic weld then re-drill.
Use an ambi safety to keep it from shifting enough for the detent to fall out the side.

This is what you need to do.

I would probably try  to over size and drill the detent hole out larger, glue in a sized plug, then re-drill the two step sized holes.  But I would likely not succeed in doing it and wind up throwing it in the trash after cutting into pieces.