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The Cornerstone Safety Thumb Ledge transforms how your Ruger Mark IV handles. Tandemkross engineered this as a direct replacement for the factory ambidextrous safety, swapping it out for an oversized, 1911-style left-side safety that gives your thumb a natural place to ride. No more awkward hand positioning or accidentally bumping the safety during rapid fire.
This is a true drop-in part. Installation takes just minutes with basic tools, and nothing inside your gun gets modified. The safety mechanism stays completely stock on the inside. The ledge itself is made from durable black anodized aluminum, so it'll hold up to regular use and won't wear through. If you want to remove the factory right-side safety lever that sometimes pinches fingers, the Cornerstone uses a factory spacer from your original Ruger box to secure everything properly.
Once installed, your thumb naturally settles on this wider ledge instead of the tiny factory safety. That consistent hand placement translates to better control of the pistol, especially when you're shooting quickly or working on accuracy. The ledge also helps keep muzzle flip in check. Competitors and plinkers alike report improved precision and a grip that feels more like a 1911 than a basic rimfire.
Owners mention the install is straightforward if you follow the provided video, and the finished result gives your Mark IV a much more refined feel. It's compatible with standard Mark IV models, though some shooters with wraparound wood grips may need minor modifications for clearance.
The Cornerstone is designed for Ruger Mark IV Standard, Target, Hunter, Competition, and Tactical models. It is not compatible with Mark III or earlier versions. If you have a Mark IV 22/45 model, you'll need to order the specific 22/45 version instead, as the internal safety shaft differs slightly between the standard Mark IV and the 22/45.
No. This is a drop-in replacement that only touches the external safety. The internal safety mechanism stays completely factory. Installation uses the factory spacer from your original Ruger box and takes about 15 minutes if you follow the installation video provided by Tandemkross.
The Cornerstone replaces the factory ambidextrous safety with a left-side only design. If you want to keep the right-side lever, you would need to skip the spacer installation. Most owners remove both the left and right factory safeties and run only the Cornerstone for a cleaner, single-side design.
The factory safety is tiny and ambidextrous, which means it can pinch your hand during shooting and provides minimal surface area for thumb placement. The Cornerstone is three times larger with a 1911-style design that gives your thumb a natural resting spot, preventing accidental engagement and improving grip consistency during rapid fire or precision shooting.
| UPC | 769498484913 |
|---|---|
| Manufacturer | |
| Manufacturer Part Number | TK24N0346BLK1 |
| Model | |
| Style | Thumb |
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