If you do in fact have Berdan Primed brass, it is easier to get a dowel close to bullet diameter, fill the case with water, while mounting case over a hole or hollow for the primer (drill a primer size hole in a 2x4). Hold the dowel in the neck, and strike with a mallet. The primer should pop out. But only do it if you have new Berdam Primers available. Then, you can use the tool as a paper weight.