Wilson Combat's 18 lb. recoil spring full size 5" 45 ACP shooting 230 gr hardball equivalent or standard pressure JHP self-defense ammunition with a power factor of 175,000 to 195,000 (Velocity x Bullet Weight = Power Factor) Average service life 15,000 Rounds. Keeping a fresh recoil spring in your pistol will dramatically reduce the pounding your slide and frame receive.