Not to get everyone wrapped up in another .45 Long (or otherwise) discussion- but does anyone know why the various .44 cartridges of the time were not deemed worthy of US Military affections? Seems to me the .44-40 had a good thing going.
There are quite a few reasons off the top of my head. One being that Colts were not commonly in that caliber and S&W also had their own cals as well - but a few S&Ws were made in 44 wcf aka 44-40. The ctg was good, but since the US did not wish to issue Winchester 1873s or 1892s or any other repeater in that cal (Colt-Burgess rifle or Whitney rifle, Marlin, etc), there was little advantage to selecting 44-40 over 45 colt. Many people did however have a lever action repeater and their favorite revolver both in the same cal for convenience purposes. For the 44 S&W, apparently the US preferred the 45 colt, and so S&W had to adapt to that, although IMO their Schofield design was better for its intended purpose
with the Army esp the Calvary than the Colt SAA.
Partly as well you have the philosophy of bigger being better, and bigger meaning more power. In 1873, the standard rifle was the trapdoor 45-70 and before that, there were 50 government rifles. So a 45 colt was more powerful than the 44-40 which was viewed as of chief importance.