When confronting the villainous Mr. Fletcher (Patrick O'Neal) and another businessman at the end of the film, David "Mo" Rutherford (Michael Moriarty) pulls a Walther P38 on them.
Thompson Submachine Gun
The militia headed by the slightly unbent Colonel Spears (Paul Sorvino) all carry Thompson Submachine Guns. They have the classic foregrip but with standard magazines and are all stockless.
M16
A few of the militia wield M16's as well. As well, inside Spears' house there are a pair of "crisscrossed" mounted M16's on display, as one would display swords.
Smith & Wesson Model 57
When the militia storm the factory, the gate guard (Harvey Waldman) uses a Smith & Wesson Model 57 to shoot one of Colonel Spears' men who was disguised as a trucker before he himself is killed by Spears.
Smith & Wesson Model 19
A Stuff-possessed state trooper (Jery Hewitt) who pulls the main characters over on the highway, impeding their escape, and attempts to arrest them by pulling a Smith & Wesson Model 19 which is difficult to see since the scene is filmed at night.