The boxer-primed copper cartridges were a pretty dismal failure. Apparently the copper wouldn't hold the primer adequately and they were prone to popping out.
Interestingly enough, though, the Benet priming system apparently wasn't an unqualified success, either, as the internal cup had a tendency to slip out of place, which would allow the round to go dead.
Scorch, the Lee-Metford Mark II, which introduced the 10-round magazine, did have a detachable magazine. I'm not 100% sure, but the Mark I* may also have had a detachable magazine.
As for the Mondragon, it was designed in the early 1880s and patented in the late 1880s, but it wasn't manufactured in anything other than one-off machine room pieces until 1901. It was also a semi-automatic.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.