Formally adopted in 1877, the I.C.1 Martini Henry was formally designated the “Arms Interchangeable, Carbine Breech loading Rifled, with clearing rod Martini Henry Mk1”. The word “interchangeable” refers to its use for both the artillery and cavalry services, instead of needing a separate design for each, as was typical of military forces at the time. It was chambered for the massive .577/450 cartridge, with a 21.3 inch barrel and an overall weight of 7.5 pounds.
I was shooting it here with 1950s Kynoch ammunition, a batch of which came into the US several years ago and can still be found without much trouble. However, it gave me significant hangfires and split cases, and I would not recommend it.