Do you find some primers fire better in a NEF blank gun than others? Mine is one of the newer ones (~2 years old), and I have a box of mixed primers but I'm having too many mis-fires and I question if I'm having more mis-fires from some brands more than others.

Have any of you found that your NEF gun prefers some brands over others? Which work best? Which should I avoid buying?

Also, any good sites to buy primers these days?