Not for use in models 52-2, Sigma Series, and M&P Series
Reduced power trigger return spring pak (draw bar plunger spring) offers 3 different springs to help improve double-action trigger performance in all Smith & Wesson centerfire semiautomatics in 9mm, 10mm, .45 ACP and .40 S&W calibers. Pak contains 1 each of 2.5, 3.0 and 3.5 pound reduced power trigger return springs to allow varying adjustment of the trigger. The factory spring is 4 pounds. These springs are particularly beneficial when used in conjunction with reduced power hammer springs listed above.