I've had very good group size with a wide range of loads in the .45 Auto just by using the bullet headspacing trick. With one of my match loads it reduced group size by 40%. As to tuning, pistol barrels are shorter and more rigid than rifle barrels, so they don't swing harmonically with the same enthusiasm rifle barrels do. With pistols, it seems like getting consistent recoil operation and motion of the moving parts and good operator trigger control are more key. …And, as I get older, good shooting glasses.
