This is something that is almost never addressed in regards to conical bullets shot from 1in 48” twist barrels. Some of the kit guns shoot conicals very well, basically because the rifling is quite shallow. But, the same twist in a cut rifled barrel, in the twelve thousandths, and deeper rifleing, often don’t shoot all that well. The issue is no doubt gas leakage around the bullet. A lead conical will only obturate so much, so sealing in a cut rifle barrel is very unlikely.
The other problem with a conical, verses a patched round ball, is the second shot. Because of the shallow rifling, and the inherent very dirty bore following the shooting of a conical, the second shot is very likely to be hard, and maybe impossible to seat properly. The only option I can see here, if you insist on shooting a conical, is to shoot a thinly patched ball for your second shot.
I have never found a need for a heavy conical on deer, or even elk. If you are having issues with a round ball killing cleanly, I would look at shot placement, or range, first, before I went to a conical bullet.
Hungry Horse