well i was told that the trigger on the SP-01 gets better with use. i was also told that dry -firing may damage the firing pin. i didnt want to take a chance so i bought a set of a-zoom snap caps for about $15 for 5. why take the chance. what i dont know is, how many pulls each one is good for. some say indefinitely, some say 3000 pulls, who knows. i also read on another forum that you can make your own by removing the primer on a spent shell and inserting a cut-to-fit pencil eraser there. anyway, if you are not sure, why take the chance?