This one is a little unusual. It started life as an "Old Model" Ruger Vaquero Sheriff's Model in .45 Colt, which cartridge has been around since 1873. The older model Vaqueros were tanks: big solid revolvers that could take a lot of abuse. They were popular with the cowboy action shooting crowd. The only drawback to them, as I see it, is that they were big— much bigger than the Colt single-action revolver they were more or less replacing. The grip frame was quit a bit larger than the Colt's and the Vaqueros simply didn't "feel right" to someone who was familiar with the Colt. Eventually Ruger listened and discontinued the old model in favor of a newer model that was much closer in size and feel to the original Colts. But that's another story, which I will probably eventually get to.
This particular old model Vaquero went off to a custom single-action smith and came back with a new lease on life: a Bisley grip frame, an action and trigger job, a free-spin cylinder pawl. All in all, it is a sweet six-gun. It is also in one of the best available calibers for a big, heavy, all-purpose field revolver: the .45 Colt. Even better, the sheer beef of the old model Vaquero makes for a revolver that can take some potent handloads. It will digest loads that would blow a Colt into many little pieces. I do not advocate this, nor does Ruger of course, but merely report that it is possible and often done. If I lived in big bear country, which I don't, it would probably be my choice for a tag-along defense pistol. With the right, custom-crafted handloads it would be excellent protection when a rifle wasn't available or just too much of a nuisance to tote.
I don't carry this revolver very much. I like it, but it is just too heavy to make for a comfortable all-day pistol, even in a good belt rig like a Mernickle. (Just for the sake of accurate data: a Colt S. A. A. in .45 weighs 37 ounces empty. This Vaquero, empty, weighs 42, the same as a fully loaded Gold Cup. Loaded with six rounds, it weighs just a hair under 48 ounces. That's three pounds, folks.)
But if you want a heavy-caliber field-service revolver that will outlast you by many years you can't do much better than one of the old model Vaqueros.