I fired my 586 S&W 357 today,I put 12 reloads through it to see how it shoots,the load was 38 special cases with 4grns of pistol powder under a 148grn wad cutter and the gun locked up,I've only just bought it and all six primers had backed out of the cases until the gun locked.I fired two cases without powder and the primers backed out half thier length,whats wrong with this thing?. Pat