I started loading my own ammo in the early 1960's. In the first couple of months, I had a couple of "Fail to fire rounds" Primer indent was normal, powder intact when they were broken down. [I can still remember the load: 180 Kling-Kor SP, 59.0 grains of surplus H4831, Alcan LR primer]
Talked to a local gunsmith/shooter/reloader about it. He asked me if I was handling the primers....which, indeed I was. He told me to avoid that.
Never had a Failure after that. Over the years, I have caught a couple of things that would have caused problems, but saw them before I assembled the loads.
One was a case without a flash hole. Several boxer primers of various makes over the years without an anvil in them.
One primer with the anvil in upside-down.
These days, I have the utmost confidence in my own loads, and expect them to out-perform factory loads in my rifles.
How many reloaded rounds I have fired in my lifetime would be hard to guess...but the number is right up there.
Regards, Dave.