General Patton was not a fan of semi-automatic pistols, and did not trust them. His first handgun in the Army was a Colt Model P (SAA), 4.75" barrel. He is credited with at least two personal kills with it, while on the punitive expedition into Mexico with General Pershing.

He bought one of the early Smith & Wesson Registered .357 Magnum revolvers. It has a 3.5" barrel.

As others mentioned, he rarely wore both.

They're both on display, with the original leather, at the Patton Museum at Fort Knox, Kentucky.

He also carried, at times, a Colt Model 1908, and a Remington Model 51, both in .380 caliber.

Follows is a link to pictures of both revolvers.

General Patton's Pistols - Colt 45 and SW 357