Ash (Bruce Campbell) wields a 12 gauge Double Barreled shotgun. He identifies it as a Remington, but it is not. The receiver and foregrip look similar to an IGA Stoeger Coach Gun with 20" barrel.
Ash displays his gun to a group of "primitive screwheads" in his famous "This is my Boomstick" scene. He uses it mostly in the beginning of the movie, then later to shoot Evil Ash (Bruce Campbell) in the face. He also uses it once during the final battle, but loses it when he crashes his 'Death Coaster' to avoid hitting the heroine, Sheila.
Despite only holding two shells, Ash fires this weapon a total of 3 times without reloading during the "This is my Boomstick" scene. He also fires it 4 times without reloading during the "She-Bitch" fight scene. (Every time he fires both shells the shot changes to something else and some soft clicking is heard. Apparently he's a very fast reloader, especially for a guy with only one hand.)
Winchester Model 1894
Ash is seen wielding a Winchester Model 1894 lever-action rifle with a "Trapper" loop handle when a Deadite appears and begins tearing up the S-Mart in the present day. Despite the fact that most lever-actions hold around fifteen rounds, Ash fires 37 shots in quick succession without reloading.
Edit: It's actually shown that simply because he has a mechanical hand he can load and fire at the same time, and rather quickly.