Origins
It was 1873. Winchester had a brand new repeating rifle in a new cartridge, the 44 Winchester Center Fire, (44WCF). Colt had a brand new revolver firing metallic centerfire cartridges called 45 Colt. At first, the Colt was only available to the U.S. Cavalry. But the Winchester was available to anybody with cash. There were several much better calibers for hunting big game, but they were single-shots. The single shot rifles were superior for hunting but there was this other problem..... Did y'all know that the Comanches shunned firearms because their bows were better for combat than muzzle-loading guns? They took on firearms when repeating arms became available. It was hostile Indians on the frontier that guaranteed the success of Winchester Repeating Arms. Once Colt got caught up on their Government contracts they looked at civilian marketing possibilities. The Colt people, being reasonably bright, were looking at Winchester's recent success with their 1873 model and noticed that the Winchester cartridge, coincidentally was very similar in size to the 45 Colt. In fact it would slip right into the cylinder of the Colt revolver. They wasted no time in offering their revolver in 44-40 on the civilian market and specially marked the barrels, "Frontier Six-Shooter". Colt revolvers and Winchester rifles were a popular match, made not in Heaven, but on a wild and dangerous frontier. The 1873 Winchester was adequate for deer if you could get close enough. There were plenty of better choices for hunting. But for conflicts with determined enemies there was perhaps no better rifle in the world at that time. The frontier was the boundary between civilization and lawlessness. There would be forts and trading posts there where you could obtain ammo and other supplies. But westward there would be no resupply. Only risky opportunity and uncertainty. It made a lot of sense to have most, if not every gun in your party chambered for the same ammo. Here's the short list of the reasons why: Arapahoe, Kiowa, Cheyenne, Comanche, Apache, Blackfoot, Sioux, etc. That was how it started back then and fun had nothing to do with it. Nowadays it might have more to do with fun than practicality.