I am in total ent with 500 Nitro on this, mirroring Forsyth's teachings of 1860. Te 12 bore ball as tremendous potential, but not with piddling charges. It needs to be moving and in today's powders, Swiss might give the best results as it is some 20%+ greater energy than GOEX.
: 140gr., a moderate to light charge for a single 11 bore(.75), will actually exit a moose, broadside, and 200gr. will exit from almost any angle, but has low velocity and less power than I'd be comfortable with on DG.
: This complete penetration is with Canadian WW cast into .735" balls, running 12 to 13 brinel.
: The 12 bore rifle usually uses a .715 ball, about 545gr. in pure lead and 530gr. in WW metal. A slow twist with shallow rifling is needed to shoot hard lead with heavy charges. I know, as I used them in my .69 and with it's deeper, faster twist, hard lead could only be used with paper ctgs. I was lucky, in that the ball size matched 2 turns of typing paper, and shot as well as patched round balls with 6 drams of GOEX powder.
: Pure lead balls expand, which limits penetration on hard objects, even with low velocity loads. A mix of 50/50 lead to WW might work just fine in the rifle mentioned but I never got around to trying it. The mix would resist flattening and increase penetraion. Accuracy is of the utmost importance. Then, a velocity of 1,400fps should be attempted, if safe for the rifle being used. That should do the trick.
: The 14 bore required 165gr. to get 1,550fps, but a 12 bore's larger ball will require something in the relm of 200 to 220gr.to get that velocity. If the rifle is incapable of digesting this charge, perhaps it isn't capable of being a DG rifle and should be relegate to North American Game like Deer, Moose, Bear and Elk.