Wolff Gunsprings M&P Full Size XP Recoil Calibration Pak

Wolff's extra power recoil calibration pak for full size Smith & Wesson M&P pistols in 9mm, 40 S&W and 357 SIG. It holds one each of 17, 19, 20, 22 and 24 lb recoil springs, plus three standard power striker springs. The stock M&P spring is 16 lb, so every spring here is heavier, for hot loads or extra cycling margin. Start with the heaviest and step down until the pistol ejects and returns to battery the way you want.

These springs are not captive. Wolff says they must be used with a solid, non captive guide rod such as its own M&P guide rod, which is sold separately. It does not fit the M&P 2.0 Compact with the 4 inch barrel.