UncleNorby
My System One made by TC just before they came out with the QLA is a 1-38 twist and will shoot bullets with a sabot up to 250 gr and all the common conicals quite well.
My personal belief is that there are two ways to shoot conicals with a QLA one is the hollow base which seals all the way to the end of the muzzle and the other is a wad over the powder a column of corn meal or such filler long enough to push the bullet past the end of the muzzle before any gas can escape along the sides of the bullet and cause deflection.