I got a SSK 38 spl in a 12 inch barrel. The reloading manuals give info for 4, 5 and 6 inch barrels using Unique, HS6, W231 and ect. Any suggestions on powder that would do better in the longer 12 inch barrel? I will shoot 125 jacketed and cast bullets in the 143 and 158 grain. Do I go to a faster powder or slower powder?