I put 25 rounds through the Black Diamond yesterday. These things were blowing up all over the place with chunks landing who knows where. It could be that since the 209 nipple was old it finally gave out and that then, since there was no pressure on the primer itself, it allowed it to explode. When I shoot them in my CVA I will have a better idea.

I just ordered a new breech plug and 209 nipple for the Black Diamond XR. I figure it is a good idea to have a spare around anyway....