You can read the exact definitions here, if you have the patience to wade through a military document. https://www.dia.mil/FOIA/FOIA-Electronic-Reading-Room/FOI

You can read the exact definitions here, if you have the patience to wade through a military document. https://www.dia.mil/FOIA/FOIA-Electronic-Reading-Room/FOIA-Reading-Room-Other-Available-Records/FileId/64737/ https://www.dia.mil/FOIA/FOIA-Electronic-Reading-Room/FOIA-R... Certain military-grade rifles that are semi-auto but can also be made to fire fully auto are classified as assault weapons, officially and militarily speaking. Civilian anti-gun activists just call anything "assault" that even looks kind of military, like a black AR-15 that might only fire .22 bullets, one at a time. By the way a .22 bullet might not stop a man unless it's a heart hit; this is why police (and bad guys) tend to use .45 or other larger caliber weapons. A .22 is quieter, less kick, cheaper ammo, and is good for killing rabbits.