Any suggestions for a good reliable pistol caliber upper? Im thinking of something in 9mm or 45 whichever has the cheapest mags. Also anyone know of a good mag well adapter?

First of all, there is a Rimfire & Pistol Caliber section, so you can read & post there.
A Mod could move this.

Second, I have had an Oly 9 conversion for 2 years & I love it. I use Sten mags &
I often take it to the range, & leave my .223's at home. Very accurate, relatively
quiet, & fun! I really enjoy taking it to the IPCS matches sometimes, as well.

There a varying opinions as to which one is best, & they all have their
good & bad points. Do the research, pick one you like, buy it & enjoy.

I'm making headway to getting a suppressed 9mm upper soon.

Good Luck,

Johnny C!

I have the 9mm and the 45 uppers from Olympic.  Both are great!  Sten mags for the 9mm, and the same 9mm sten mags also load for the 45, but the 45 also uses Uzi mags.