Tandemkross Cthulhu Lower for Ruger Mark IV and 22/45

Tandemkross built the Cthulhu to replace the polymer grip frame on the Ruger Mark IV and Mark IV 22/45 with a fully metal one. It arrives assembled and upgraded with Tandemkross parts throughout, so it takes an existing upper straight away instead of turning into a parts order and a bench session. That is the difference between this and a stripped frame: no pins to chase, no springs to source, no fitting.

The trigger guard is enlarged for big hands or gloves and hooked for more points of contact, and the backstrap is textured to keep the grip from shifting under recoil. Fitment covers factory and aftermarket Mark IV and Mark IV 22/45 uppers, so a swap or a fresh build both work. Finish is black.