The revolver is a fairly common weapon located in Supermarkets and residential areas. It holds 6 rounds of .45 ACP ammo. M1911 magazines can be converted to ACP and vice versa, but the inital change will cause the loss of a single round (M1911 magazine holds 7, ACP only holds 6). Compared to the M1911, the Revolver is more accurate due to longer sight radius.
UPDATE: This weapon's body-damage was dramatically lowered in the 1.8.0.3 update.