"Machine pistols" refers to compact firearms that combine the characteristics of both a machine gun and a pistol. They are able to rapidly fire multiple rounds like a machine gun, but are smaller and more maneuverable like a pistol. Full definition
Thompsons can also be had without a stock, becoming, when converted to full automatic fire, a dandy machine pistol, a tremendously effective short - range devastator. (religion-online.org)
Moriarty would profit handsomely from that because he operates an enormous secret munitions factory, turning out everything from machine pistols to gigantic cannons. (rogerebert.com)
When you pick a character like a giant with a minigun you hope that he will wreak havoc to every enemy on the map, but in reality his minigun does the same amount of damage as someones machine pistol and he goes down just as quickly as the tinniest character. (ticgn.com)