I didn't really need a tiger/water buffalo rifle, ie: 14 bore, and the 16 bore of similar rifling twist will handle a smaller powder charge for higher vel. and flatter trajectory, yes.
Dan's 16 bore runs over 1,700fps with 140gr. Swiss, while mine needs 165gr. GOEX 2F to get just 1,550fps.
A 437gr. ball will handle anything I am likely to need it for, in B.C. The 14 bore ball of 482gr. is not needed. There seemed a large difference in vel. per grain weight.
I read Forsyth's little book and HAD to have a 14 bore rifle, it's a simple as that. A 16 would have been fine, for a "bore" rifle as well as using less lead and powder.
Indeed, 20's work too, but they are so tiny in comparison.