Splendid.
The American technique seems to be more dated or suitable for earlier tactics, but I don’t know that much about it. Is it a holdover from older European techniques?
Honestly I have no knowledge of the British Army of the 1860s so can’t really comment. Given the Crimean War only ending five years previously, it’d be interesting to see what would have happened at First Bull Run if it had been a British force rather than a Confederate one. Though likely the Union Army of 1865 would conversely have been more capable than the British Army of 1865.
The British (along with everyone else) tore the cartridge paper with their teeth.
They stopped this after the Indian mutiny.
Indian troops did not put pig/beef fat in their mouth (& hence become unclean) which led to said mutiny.