I have a number of TC Hawlens with 1:48" and 1"66" barrels.
I use Hornady .490's with .015" prelubed cotton patches for range loads of 50-60grns Goex FFFg, but need the thicker .018" prelubed pillow ticking for no patch burnout, best accuracy, etc when using hunting loads of 80-90grns Goex FFFg.
PS: The accuracy of both twists are virtually equal so don't fall for the old wives tale that 1:48" twists don't shoot round balls accurately as they most certainly do...enjoy!