American Rifleman by Dave Campbell posted on July 24, 2021
To understand firearm development, it is necessary to have some knowledge of the economy during their progress. The Civil War brought about a great increase in economic opportunities—hence industrialization—to the Union. Manufacturing business grew at a phenomenal rate. The war created a huge market for firearms and fueled the development of their technology. While the waging of war created the demand, it was the Reconstruction period after the war that brought about a maturation of that booming economy. The U.S. military—primarily the army at that time—needed better firearms with which to serve the country.
Single-shot and repeating rifles fed by cartridges that were ignited with a primer pressed into the center of the rear of the case replaced cap-and-ball muzzleloaders and rimfire-primed cartridges. Revolvers—which had progressed nicely into the cap-and-ball technology—began seeing their own cartridge development to centerfire-primed rounds. They were very popular with the cavalry because they could be operated with one hand and offered as many as six shots before requiring a reload.
Colt rather quickly came out with a Benet-primed .44 Colt cartridge for its Richards-Mason conversion of the 1860 Army. The actual diameter of the heeled, outside-lubricated bullet was .451"to .454", and it featured a 225-gr., conical lead bullet in front of 23 grains of FFg blackpowder for a velocity of 640 f.p.s. and 207 ft.-lbs. of energy. Charles B. Richards, an engineer at Colt, and William Mason, a gunsmith who came to Colt from Remington in 1866, worked together on the .44 Colt cartridge, which was introduced in 1871.
The Richards-Mason conversion was a stopgap measure as the company retooled and set up to manufacture what would become the Colt Model 1871-72 Open Top revolver. This revolver was chambered in the more powerful .44 Henry Rimfire cartridge, a major step up in power from the .44 Colt. It was capable of kicking a 200-gr. conical ball bullet out at 1,125 f.p.s. with 568 ft.-lbs. of energy, though these numbers are probably from a rifle.
More:
https://www.americanrifleman.org/content/the-45-colt-history-and-performance/