Your cartridge is a .577/450 made for the Martine-Henry rifle about 1871.Early Martine henry rifles had a long lever action because this cartridge was origionaly made of rolled up brass shim and needed the long lever action to remove fired cartridge as it tended to grip the chamber walls when fired .Your cartridge is the later type which is the same as modern type.Originale bullet weight was 480 grains
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