- I also have a pistol that Taylor built for me. It has a GM .45 barrel with 18" twist and a .54 piece of rifle barrel with a 66" twist. I use 25gr. of 3F in the .45 bl. and generally 55gr. to 65gr. 3f in the .54 bl. With that charge, the slow twist .54 is quite accurate and kicks much like my 4" M29 - much more satisfying than the little POP from the fast twist .45 bl.
I will mention here that that one hold group Taylor spoke of, we've done several times, enough to know it's accurate and not accidental. Those groups comprises of 5 shots making a single hole - however large that hold might be. With the .60, it's likely to be from 1" to maybe a 1 1/2" centre to centre group. We've both done that, with that .60 cal. pistol. I'll also note here that there are VERY few modern pistols or revolvers which can match the accuracy of muzzleloading pistols.