We were; the 1873 model, both rifle and carbine in .45 cal.
Actually, the military tested the Springfield against the Winchester and Spencer, and found the Springfield to be superior in accuracy. Military practice still relied on volley fire at the time, and it was felt that single shot weapons with volley fire could superior to the possibility of greater firepower (through the use of repeaters), if in the hands of America's existing foe; the American Indian. And, it was generally held that the Indian did not hold a significant supply of repeating arms. this was disproved in 1876 at the Little Big Horn.
Some outfit made a shooting repro of the trapdoor springfield years ago. I heard the originals had problems with blow-out from the door in the breech.
If I had the money back then, I would have bought one of the repros. I think the cartridge was a .45/70.
Another gun I'd like to get is the Sharpe's Buffalo gun. There is an outfit in Montana that makes good repors of them that run well over $1,000 and they have a waiting list. I think some Italian fiorm makes a repro of them that is of less quality but cheaper. I think they came in .45, .50 and .54 with different powder charges.
Really like that movie "Quiggly Down Under".