95% of the time the problem will be high primers - not being seated all the way down in the pocket. The firing pin has spent most of it's energy pushing the primer deeper into the primer pocket.
The other 5% of the time the problem is mechanical - dirty firing pin channel, weak mainspring, etc...
If the primer ignites but the powder doesn't, the bullet will be kicked out of the case and will usually be lodged in the barrel/throat and unburned powder will be everywhere.
Last edited by Hammerhead; May 27, 2012 at 06:45 AM.