Wilson Combat Heavy-Duty Recoil Springs are made combat tough to repeatedly take a pounding yet show remarkably consistent performance every time a round is fired. Keeping a fresh recoil spring in your pistol will dramatically reduce the pounding your slide and frame receive. Features: Recommended use - full size 5 inches .45 ACP shooting 185 grain/200 grain standard pressure target or JHP self-defense ammunition with a power factor of 145000 to 170000 (Velocity x Bullet Weight = Power Factor) Average service life - 3000 rounds