Ruger 22/45 lower in aluminum is the way to go - TANDEMKROSS Tandemized Ruger Mark IV and Mark IV 22/45 Cthulhu Lower

Built my own 22/45 using this lower and a Volquartsen upper. The TandemKross Cthulhu lower is simply incredible. Firstly, it's machined aluminum, not polymer, so tolerances and fitment are far superior and it feels great in the hand. Comes fully assembled with ALL of the TandemKross bits and pieces to make it great. Victory trigger, extended mag release, larger slide stop/release, thumbrest safety and a thumbrest for your offhand too, made by Strickland, plus TandemKross's hive grip, which feels great. Also worth noting is the slide stop pin that sticks up in the back is fully aluminum and not polymer like the stock ones, which are prone to breakage.

If you are considering building a steel challenge pistol, do yourself a favor and get this lower and an upgraded upper and call it a day. Buy once, Cry once but you will be crying with a smile on your face when you see how smooth these pistols can really be.

Dont sleep on this! Buy one and get to the range!