I also have a TC Contender in .357 Max. I had a 14 inch heavy barrel made up by Bullberry Barrel Works. I cannot get the gun to shoot under 5 inches at 50 yards. It could be my technique, but I wonder, do you have any good, accurate handload data for the .357 Max?
U might try here:
http://handloads.com/loaddata/default.asp?Caliber=357%20Maximum&Weight=125&type=Handgun&Order=Powder&Source=