I have a Lee Auto Prime II also. The problem with mine is it won't let all the primers feed by gravity due to the curvature of the plastic tubes. The last few have to be pushed into place with a toothpick or paper clip. I've never detonated a primer but I have crushed several. Another issue with it was when using it on their hand press the cover would come off and primers would fly all over the place. I saw the "new and improved" model in their catalog, it looks like it may have been changed to feed the primers better, and to be a lot cheaper for them to make.
It was replaced with an RCBS APS bench mounted unit. My RCBS Piggyback II progressive conversion has the old tube type primer feed on it which works just fine, but I'd rather have the newer auto progressive PB with the APS primer feed. Maybe when I strike oil in the backyard.