The conicals used in ML's of the (that) day were not particularly good in ML's, Bob, and were mostly Minnie-type. Today, the problem is with 48" to 66" rates of twist and conicals
too long for those rates of twist.
Stable (barely) in the air, but not after they hit something of substance. If you do not get straight line penetration, you have a wounding machine, not a killing one.
Today, when used in the PH Whitworth or the Volunteer rifle, or specific rifles made for them, grooved lubricated bullets work especially well on our moose & as such,
would also work well on buffalo.
The TC Hawkens & others with buttoned 48" twist barrels - not so much.
When dealing with dangerous game, where penetration is of utmost importance, it was found in the jungles of India, that conicals were very poor performers compared
to round balls. This is why conicals did not gain much of a foothold for shooting large game until breech loading was invented and alloyed conicals could be used to good
effect on the dangerous beasts. Alloys needed for deep penetration, did not shoot well in the muzzleloaders, thus their not gaining popularity until the 1870's.