I don't think they will work. My son has a few cap guns, and we play all the time, half the time, the caps don't even go off, not even on the 2nd or third try. That makes for a dangerous set up, you will have a difficult time remembering which chambers fired and which ones didn't. I know for a fact that the cap gun doesn't produce enough flame to ignite powder consistently, you may get one or two shots off, but if there is even a little humidity in the air, it will not work. If it does, let me know, I'll be amazed!! I'm just worried about a slow ignition, which would lead to a potential accident, god forbid. Also, it depends on the nipple size for your gun.