Originally Posted by oli700
with what and why ?
If you bought it used, the last owner may have installed a higher pressure recoil spring. Many shooters do this if there going to shoot +P or ++P loads to avoid damaging the gun.
Shooting standard velocity ammo with a spring rated for higher velocity ammo could cause the problem you described. I'd pick up both standard and +P ammo and see which functions best.
Then you'll know.