I have a Black Diamond XR and am on my third breech plug nipple. Them springs just don't last forever. I am guessing the rifle not being new, was shot and then sat on a shelf for a long time. Maybe that spring was weak, who knows. I would just order the new nipple for it. Also those rifles can shoot #11 caps and Musket caps as well. I use the same 209 primer as you did. My last one has over two hundred shots on it.