The jammed cartridges at the Little Big Horn were the result of several things - verdigris build-up on the copper cases as a result of the contact with the all-leather 'Fair Weather Christian' belts, was one, but the heated barrels from excited Carbine fire were another - effectively 'fusing' the case to the chamber upon firing, and causing extraction failure.
Apparently that was never something planned for during initial testing.
When that happened - the copper case was well and truly 'stuck' unless prised out with a knife blade, and there are numerous examples extant of that, as well as several accounts of Indians clearing the chambers of those Carbines after the battle with ramrods and such.
The new brass case eliminated most of those problems, since it expanded at a much slower rate than copper and retracted quicker, as well.
The use of the 'horse holder' lasted until the Cavalry's end - though those horses were inured to gunfire and would've been grazing on what could be found, while the horse holder anxiously looked for his bunkies.
In a way - it still exists - except the 'horse holder' is the Bradley Commander and the 'horses' are in defilade as the Troopers fight dismounted - and 'this' time - the 'horse holder' can engage from his position in the turret...
One thing the various Armies of the time had in common when it came to the single-shot weapon was a fear of untrained, excitable soldiers using up their issue to no good purpose, and scared soldiers pull a lot of triggers...
As such - those Armies had little use for magazine-fed weapons and more use for aimed single fire.
Early military bolt-actions had a 'magazine cut-off' for that purpose - with the soldier firing single, well-aimed shots and using the magazine's rounds in the attack.
Today - it's different, and 'fire suppression' is the Name of the Game , and the concept of 'Marksmanship' is taught not on the Range, by experienced instructors - but indoors, on a computer-simulation, but 'way back when' a soldier or Marine earned extra pay for his proficiency with his weapon.
For it's time - the Springfield Trapdoor was an effective, deadly weapon, firing an accurate, heavy bullet - as did the Martini.
Serving in harsh locales, against tough fighting men - they did the job asked of them, like the professionals who carried them.
Vaya,
Scouts Out!