I am loading 158gr semi jack hp made by Zero for a gp100 357. The press is a Lee classic turret. The dies are their carbide 4 die set. I seat the bullet to the crimp groove(on these bullets it's barely even an indentation more like a scored area) and crimp in the factory crimp die. It seems like some of the rounds get a good firm crimp and some I can actually spin the bullet in the case. There is no bullet movement in or out just spin. I might get 5 to 10 like this every 50 to 75 rounds. In the past I single loaded them and they shot fine I just can't figure out why this is happening. Brass is Win and this is maybe the 3rd time they have been loaded.