Howdy
Left to right in this photo, the original Benet primed version of the 45 Colt, Benet primed 45 Schofield, 44 Russian, 44 American, 44 Henry Rimfire, 44-40. Since these rounds are filled with Black Powder without any airspace, the length of each round is a pretty good indicator of their relative power.
The 44 Henry was a copper cased rimfire round. It held about 26 grains of Black Powder under a 200 grain bullet. Not a power house, but about all the old brass framed (actually bronze) toggle link rifle could stand. the Henry's successor, the 1866 Winchester had the same relatively weak toggle link action and brass frame, so it too was chambered for the Henry round. When the Model 1873 Winchester came out, it had an iron frame to be able to handle the more powerful 44-40 round, which held about 40 grains of powder under a 200 - 230 grain bullet.
Some of the very early 1860 Henry reproductions that Navy Arms had built were actually chambered for the Henry round, but the ammunition had not been commercially available for years, so later models were chambered for 44-40 and 45 Colt.
My Uberti 1860 Henry is chambered for 44-40. I have a few old Winchesters chambered for 44-40 too.
While the 1873 Winchester was stronger than the Henry and 1866, because of the iron frame, the toggle link action inside was still relatively weak, so 44-40 was about as powerful a round as you could chamber in it. The 1873 Winchester was also chambered for 38-40, 32-20, and 223 Short.
When the 1892 Winchester came along it had a much stronger action, but its most common chambering was still 44-40.
The real beauty of 44-40 is that it and 38-40 are the bee's knees for the Black Powder shooter. The brass at the case mouth of these rounds is much thinner than a 45 Colt, so the brass swells to seal the chamber better than the thicker brass of 45 Colt. With the chamber well sealed, almost all the fouling stays in the bore where it belongs. 45 Colt rifles, with their thicker brass are often plagued by blowby that lets fouling past the chamber and into the action.