I tried a pure lead .684" ball that engraves only about .0045" on each side as a bare ball load in my Husky double 16, heavy crimp to hold the ball in the oversized brass case. The rifled, right bore has a .703" groove with a .675" bore diameter. Initial accuracy with the ball I tried, along with 14 gauge wads in brass 2.4" cases, shot fairly well at 30 yards - about 2 1/2" and pretty mucht o the sights. I then tested a 16 bore ball, that's .662", with a heavy .030" denim patch, lubed with mink oil. These make a might tighter group yet and on the sights. I was using a mere 3 drams of 2f GOEX - that's 82gr. The case will hold a lot more powder, but is it necessary. For moose or elk, I'd run that up to about 120gr, but probably not any more - not needed, as this will duplicate most of the round ball 16 and 14 bore mid 19th century rifleds for India - tiger, buffalo, elephant. the straight rifling is a close range deal - maybe 80 yards tops, but even that seemingly close range, what the real max range is depends on what the accuracy is like.