TANDEMKROSS Cornerstone Safety Thumb Ledge (Ruger Mark IV 22/45)

The 22/45 borrows the 1911's grip angle but not its thumb shelf. The Cornerstone bolts an oversized, 1911-style ledge onto the pistol's factory manual safety so the shooting thumb has somewhere to rest, which locks the grip in place and stops the hand from rolling under recoil.

It is a drop-in part. The Cornerstone attaches to the existing safety and does not touch the internal safety mechanism, so the pistol's safety function is unchanged. Installation uses the factory spacer that shipped in the pistol's original box, documented on page 23 of the Ruger manual; if that spacer has gone missing, TANDEMKROSS sells a Safety Spacer and Screw kit for $4.99 as a separate item.

Fitment is 22/45 only: the Mark IV 22/45, 22/45 Tactical, and 22/45 LITE. Standard steel-frame Mark IV pistols take a different part number, and the Cornerstone for that frame carries a caveat about clearance against target wraparound wood laminate grips that does not apply here. Shooters building a full 22/45 grip package usually pair this with the Accelerator Forward Thumb Ledge on the opposite side of the frame.