Back in the early 1970's , used a Lee target minnie , .580 , in a repro. Harpers Ferry rifle w/ a peep sight. Gave the minnie a slow start to protect the skirt using 80 gr. FG black powder. Rifle was very accurate giving a 3,5 in group at 100 meters. HOWEVER , the the trajectory had an 8 " rainbow in it. This was before range finders , so hunting with a rifle with a built in 8" rainbow was challenging. Shots at deer to 60 yds, were doable , but missed a fine buck not being able to figure the point of impact at further distances. That particular minnie was an instant killer . I shot a big doe face on at 25 yds. high in the chest. the ball passed through 17 " of chops and bone before it stalled.
Sold the rifle to a friend and he continued to kill deer w/ it until he became frustrated with the rainbow trajectory . Both of us graduated to long rifles and were more able to make longer shots in the deer woods. ......................oldwood