First successful double-action revolver was the Adams revolver patented in 1851 in Britain. Although double-action, it was cap-and-ball and loaded at the muzzle with a separate powder charge. I believe S&W made double-action revolvers in the 1850's, but they were chambered in .22 caliber. Can't find info on the interwebs about this, so I am recalling a book I have at home and can reference when I get back.Kitsune wrote:One item I am looking at is the first powerful double action revolver. . . .The .41 LC is a bit anemic
Edit: I want to thourily explore existing pistols before going to custom weapons
In the 1850's, your character would most likely have carried something along the lines of a Colt M1851 Navy or 1848 Dragoon, depending on whether concealment would have been a priority (Dragoon is very large compared to most pistol's today).
In the 1860's, he might have switched to a Colt 1860 Army, which would be more powerful than the Navy and more practical than the Dragoon. He might have converted it to use metallic cartridges instead of the musket-like cap-and-ball system. S&W held the patent on cartridges during this decade, but many individuals converted their Colts. (Again, this comes from a book I have at home, will need to double-check the facts).
In the 1870's, he would either use a Colt 1873 SAA or S&W Model 3. Both used cartridges, but the S&W would break-open at the top and was much easier to load at the expensive of having a less powerful (but still strong) cartridge and being regarded as somewhat less sturdy and reliable. It is unlikely that someone who has depended on single-action revolvers for decades would switch to a double-action at any time before the 20th century.
If concealment is not an issue, the character would probably also use lever-action rifles such as the Winchester M1873, which was more powerful than almost any revolver, held more rounds, and had much greater range and accuracy.
This character would probably not switch to .38 caliber revolvers that became popular in the early 20th century, preferring the more powerful .45 Colt or .44 S&W he has been using for decades at this point, but would probably start using the .45 ACP Colt 1911 after its effectiveness was proven in WW1, and would use it until at least the 1980's or 90's. At this point, he would either keep using his trusty 1911 or switch to a high-capacity 9mm, probably a Glock. Whether he would make this switch depends on whether can use hollow-point bullets or needs to use special rounds (silver, holy water, etc). With HP ammo, the modern 9mm has much greater ammo capacity than the old .45, substantially less recoil, and virtually indistinguishable lethality, a no-brainer for someone who regularly tangles with dangerous creatures. Without it, the .45 ACP has much greater killing power and he might stick with that.