for the most part it seems to be alright with most modern centerfires, i still always use snap caps. there seems to be some concern about stress on roll pins, or a firing pin block causing a break, or two piece firing pins. a lot require them to be dry fired to field strip, such as a glock, or springfield xd. i believe the beretta 92fs is one with a 2 piece firing pin and they recommend not dry firing, i'm not sure if that's for "just in case" or they noticed an issue in testing. you have other guns such as the cz p-01 which had to be dry fired 4,000 times without a failure, it's a double roll pin gun which is what some people worry about breaking... just for the record, i have a p-01 and still use snap caps though. what specific guns do you have? btw, rimfires are not recommended to be dry fired.