25 SST Build: Chasing Sub-MOA Groups at 3,170 FPS

Ultimate Reloader's Gavin Gear takes on another Sherman Wildcats project in this build, the 25 SST, a 25-caliber cartridge from the Sherman Short Tactical line designed to push bullets faster than any 25-cal build the channel has done before. The 30-degree shoulder trades the sharper Ackley-style angle for better feeding while keeping magnum-level case capacity, and it's paired with a 28-inch Krieger barrel at a fast 1:7.5 twist to make the most of that capacity.

Key points

• Cartridge design: The 25 SST uses a 30-degree shoulder instead of 45, which Sherman Wildcats built in for more reliable feeding without giving up magnum powder capacity.
• Build process: Gear used Rifle Builder Pro software alongside a BAT Igniter short action, Krieger barrel blank, Foundation Genesis 2 stock, and Hawkins M5 DBM, with the chambering and threading work going smoothly throughout.
• Rocky start: Early loads with Berger Hybrid and Blackjack bullets produced velocities over 3,000 fps but groups hovering around an inch, pushing Gear into methodical load-development detective work.
• Breakthrough load: A ladder workup with Hornady's 138-grain A-Tip and N565 powder eventually produced a five-shot group of 0.379 inches, about 0.36 MOA, at roughly 3,170 fps.
• Still a work in progress: Gear notes the standard deviation on that load could still be tightened for long-range consistency, even though group size is already excellent.

Quick take

This is a solid look at how wildcat load development actually goes: messy, iterative, and dependent on patient bullet and powder swaps rather than one magic recipe. Anyone chasing extreme velocity in a precision build will find the troubleshooting process more useful than the specs alone.

Watch the full video: Ultimate Reloader