Ttoes
Any idea what the velocity was on those rounds? When I loaded my 45-70 with 300gr jacketed to an estimated 1800 fps, 10 rounds was more than enough. I do have lots of fun with this Handi, however, 2-2 1/2" groups at 100 yds with the open sights if I pay attention. I use 45gr Pyrodex and 405 gr wheel weight bullets with Alox liquid lube, or a slightly hotter 34 gr Reloder 7 with the same bullet. Hot loads are for people with excellent, hard teeth (harder to chip).
You discovered why, in about 1873, the loads for the trapdoor carbines were reduced.
aka Trapdoor