1 in 48 is not to fast for RB . that is a myth
spend the time to work up a load and it will give 1 to 2 inch groups out to 100 yards .
when the hawkens bros left St louis , the 1 in 48 was the only twist the continued to use .

1 in 48 is also not to slow for conicals . again you just have to work a load and chose the right conical . many original long range rifle were rifled in twists as slow as 1 in 110 and still held sub 2 inch groups at 40 rods .

i have an original Stutzer at has a twist rate of i in 90 and it shoots conicals ver well . infact it was designed for it .

you may find that for sabots though you need a faster twist and not so deep rifling .

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