My rifle is an early 70s vintage T/C Hawken...I'm not sure of the twist, but I believe it is a 1 in 48 , which would be a compromise twist to handle both round balls and conicals reasonably well.. Whatever it is, it works because the rifle is accurate with both round balls and several different conicals...
It's a .50 cal and I am currently shooting the Noexcuses 460 grain conical ahead of 80 grains of triple F 777....This bullet loads easily and is very accurate in my rifle.. For years I used a PRB with 90 grains of 2F Pyrodex..That worked well also.. Then a few years ago I wanted to go to a heavy conical for an elk hunt..I tried the Noexcuses and they shot so well I currently use them for an all around load..