Tom... if you go with a 1x prism sight with the reticle etched on the prism, you still have a black reticle even if the battery in the scope goes dead... I have a Vortex Spitfire that I tried for my PCC... I don't like the layout of the reticle, but it is always available
if you decide to build a 9mm, give a shout... I've put together 2...a New Frontier Armory and a Palmetto State Armory with a billet lower made for them by NFA... a friend built one for his grandson with a PSA forged lower... all Glock magazine format... the NFA was originally a straight blow back, and now has a CMMG radial delayed bolt and barrel (there was a lot of R&D for me on that one to get the magazines straightened out and later an extraction problem at about 1200 rounds) and uses a hydraulic buffer and 142 power factor loads for competition... the blow backs are pretty straight forward (you might start with about a 6oz buffer and stock AR spring...... my PSA currently has a 7.5" barrel as it was a contender for the truck gun, but is considerably heavier than the G17w Recover Tactical brace...if you want to use a 5.56 lower, an adapter from MEAN ARMS converts a PMag to 9mm and works the bolt hold open... I use the longer 40 round stick mags for competition, and don't need a bolt hold open... I broke a bolt hold open with a mag well adapter for my SBR that used Colt mags.... regards Les