I have recently had that problem and had 4 which did not fire that were CCI and 2 which were Win primers. It was not the way they were put in or the rifle. I tried them repeatedly in the rifle and in another rifle. All of the other loads which were loaded at the same time the same way worked. I removed the primer and put in another with the same powder/bullet and they worked. This happened with the same lot of used in 3 different cartridges(6mm Rem/308win/257Roberts) so it was not the brass either as the same brass worked with another primer and no problems with my old primers. I think QC has slipped with the pressure to produce more primers. These were more recent purchased primers. The older primers I have(some even from the 1960's) have all worked. This is the first time since I started reloading in the early 1960's that I have had a dud with any of my reloads. I am sure it is not the rifles or the loading procedure. It is the primers. You can be sure I will use my older primers for hunting loads and the newer ones for practice/fun loads. Usually I do it the other way around.