For serious shooters who shoot 20k rounds / year or more
Highest quality recoil springs available.
Recommended spring weights:
IMM Open 9mm/38s 7 lbs, 8 lbs, 9 lbs Government
5" and 5.4" Sight Trackers .40 S&W with competition loads 11 lbs-14 lbs Government
6in Strayer Signature Limited 9 lbs-11 lbs Government