The old 8 and 4 bore guns were essentially really big shoguns.
I bet with a full brass shell and a hard lead bullet at 1600fps @ 1oz, a 12G could take a bufffalo, but it not be as effective s just using an appropriate rifle. If it was that effective, it would have been done most likely. Think about, most of what we know today in gun design came from turn of the century (20th century). There has been a bullet revolution in the last 20 years thanks to better metallurgy. most efforts on shotguns is on improving range and accuracy on midsize game rather than development of ammo for large game.
