The feds use slightly modified pistols in some scenarios that do everything except launch a bullet. I don't remember what they call it, but it's a real gun with the recoil spring modified and it takes some kind of "blank" ammo. You load the magazine with these just like normal, when you pull the trigger it's slightly louder than the hammer click, and it cycles another round. It's awesome but i don't remember the details of it.
Sent from my Galaxy Nexus that ate your iPhone.