not all 22rf ammo can be used in some pistols. jams are aggravating & may be made more unsafe by a moments trigger control without due reguard to muzzle direction. for std velocity ammo, Winchester(i've no position or represent the company) seems to solve many hurdles by consistantly delivering lots'a good range time unbroken by down time caused by an hung up fired cartridge. this is due to it not being built better. it is the faster impulse powder that enabel that fun without getting into pressure trouble. the Winchester chemist should confirm unless it is a trade secret. my 22/45 was having ejection problems (it is clean & maintained) with some makes of rf untill i ran into this (to me)little factoid, and my 22/45 has been humming since. there was no need to return to the factory as nothing mechanically was wrong, though at the time i thought the spring was too strong and deserved a haircut. hope this may alleviate some of those wierd stopages and further your range time. keep your powder dry. 400corbon