Any calibre Rb and any pre charged but would prefer sub 12,,,,,and large shot count which I don't get with fac. Of course its overkill but I don't use them just for rats, Don't have a use for 3 of them so this ones going. Saying that, Its an excellent ratter due to the short distance you can focus down too and its 5x mag. If your not sure buddy then try youtube, Plenty of clips on there for you to judge.