Since this is the handgun forum, I'm assuming the OP intended to limit this discussion to handgun cartridges. While I own and enjoy handguns in .22LR, .32 ACP, 7.62x25 Tokarev, 9x19 Parabellum, .38 Special, .357 Magnum, 10mm Auto, .44 Magnum, and .45 ACP, if I were going to be limited to just one cartridge I'd have to choose .357 Magnum. My reasons are as follows:
While I own and enjoy several bottom-loaders, I'm a wheelgunner at heart. Out of my collection, this pretty much rules out everything but .22LR, .38 Special, .357 Magnum, and .44 Magnum. Of those cartridges, I view the .357 Magnum and .44 Magnum as being the most versatile so the decision really becomes a contest between those two (and choosing between them is the hardest part). While I think that the .44 Magnum is probably a bit more versatile ballistically, the .357 Magnum gets the edge because it can more easily fit into a more size-efficient package. The smaller size of a .357 Magnum is more important to me than the impressive ballistics of a .44 Magnum because my primary reason for owning handguns is self-defense and I just can't find any comfortable way to carry a S&W N-Frame when its over 60 degrees outside. So, if I had to sell all of my handguns but one (an absolutely awful thought by the way), the one I'd keep would be my S&W M66 with 2 1/2" barrel.
While I own and enjoy several bottom-loaders, I'm a wheelgunner at heart. Out of my collection, this pretty much rules out everything but .22LR, .38 Special, .357 Magnum, and .44 Magnum. Of those cartridges, I view the .357 Magnum and .44 Magnum as being the most versatile so the decision really becomes a contest between those two (and choosing between them is the hardest part). While I think that the .44 Magnum is probably a bit more versatile ballistically, the .357 Magnum gets the edge because it can more easily fit into a more size-efficient package. The smaller size of a .357 Magnum is more important to me than the impressive ballistics of a .44 Magnum because my primary reason for owning handguns is self-defense and I just can't find any comfortable way to carry a S&W N-Frame when its over 60 degrees outside. So, if I had to sell all of my handguns but one (an absolutely awful thought by the way), the one I'd keep would be my S&W M66 with 2 1/2" barrel.
