Depends on who made it, I guess. I've shot some Russian stuff in the past which occasionally seemed underpowered in some of the rounds. But then a lot of their ammo uses pretty smokey powder so hard to tell really if it's firing differently or maybe some of the charges are just a little heavier on the powder than other rounds. Never had that trouble with American made stuff. If it cycles the gun ok, it maybe just difference humidity today vs when you last shot it? Shooting outdoors vs inside will definitely seem different just due to noise factor.