I have been recently setting my Xtreme and Berry's DEWC's flush and rolling the case mouth onto the radiused shoulder of the bullet. This eliminates the risk of breaking the plating. For me they have shot extremely well in my 6" 686 with HP38, Bullseye and Titegroup powders.

Just a thought to try perhaps to eliminate the variable on the crimp onto the plating, the Xtreme does have the knurled crimp ring where as the Berrys' is smooth plating with no specified crimp area.
Karl