I've made pistols too, around pieces of rifle barrel, and they shoot pretty well, but not as well as a faster twist. I made a .45 cal pistol out of a brand new piece of cut-off .45-70 bbl from Numrich. It was 10" long and had a 1:22" twist and was parallel 15/16" AF. I could cover all five shots @ 25 yds. with a quarter, using 25 grains of FFFg GOEX and a .018" denim spit patch. Daryl has a .54 cal rifle cut-off barrel on his pistol, and uses light rifle loads (~60 grains) for great accuracy.