I load 357 Max for a 10 1/2" Ruger not a Contender, but I have found a relatively heavy roll crimp helps with accuracy and extreme spread with Fury 180 gr jacketed bullets. 296 has worked better than 4227 for me, but 300MP has been best overall. I'm getting 1650 fps, low ES and 2" groups at 50 yards. Starline brass and either CCI400 or Rem 7 1/2 primers. 4227 has been good with cast bullets.