For complete description with photos take a look at:

http://www.rockymountaincartridge.com/page10.html



I assume that the primer ignited, because the contents of the shell were ejected. Either the primer is not hot enough to ignite the powder or the powder is some how contaminated.



I would go back to the beginning. Make sure the primer hole is clear. Seat the primer, then seat it again. Make sure the inside of the case is dry and clean. I would run a patch inside the case to be sure there is no oil left from the factory. For my own peace of mind a would take a few grains of the powder and place it in an open container, a metal jar cover and ignite it. Just to be sure.



It really has to be something very simple.



Pete

I have shot lots of brass shells, but with black powder.
The problem with smokeless is the amount of pressure that has to be generated to make it build its gasses, whereas with black, it actually explodes. That is the easiest way to describe it in lay terms I would look at the wads, and try using conventional wads instead of a plastic one.

While I don't reload them myself, I have seen on the SASS wire plenty of comments and advice about loading brass shotshells. The general rule is that wads have to be one gauge larger than normal (i.e. 11 gauge wads in a 12 gauge case) in order to get a good seal as the brass is so much thinner than plastic or paper.