A friend brought over ten rounds he had made, which had failed to fire. The primers showed a little tiny mark from where the firing pin had lightly struck the primer. We reset the primers deeper and then he tried to fire them again.
Everyone worked just fine. For most of the fail to fire rounds that I have seen, the primer not being seated correctly seemed to be the problem.
Some other problems I have seen: These are my dads primers, I found them in the garage when I was cleaning.
I found this can of powder and it smelled pretty bad, but I thought it might be good, so I used it.
I would venture to say the primer is going to be the problem. Try to re-seat it a little deeper next time, then if they fail to fire, try to reset it deeper before disassembly.
Inside Every Bright Idea Is The 50% Probability Of A Disaster Waiting To Happen.