Thank you Dave and Mike, appreciate the response without the negativity of some other guys that just what to throw insults and tip over the table.
I'm glad you didn't take offense to my post but yes, it's real. I've been doing this, not as long as some, but for so long now that I kinda assume most everyone that loads and shoots a lot has run into this. I've seen posts where people blamed the primers, usually a relatively hard one like a cci, because the problem went away by swapping out with say 205's, a softer primer. Logically, the harder primer does it more commonly and yes, a softer primer can often make the issue go away through fireforming. At that point, either works fine.
It's been a long while back and I wish I had saved it or knew where to send you but I read a good article or study on primers that went into great detail about them. Composition may even be different these days but one thing from reading it that stuck with me was that primers used a silca product(glass) in the formula and for optimum ignition, the primer compound needs to be hit with enough speed and energy to really shatter that compound, ideally into a dust. Breaking it is one thing but shattering it into dust is something else. I relate that a lot to how ignition in our equipment is so critical. Anything that cushions or deadens that blow to the primer is bad. Just because it goes off doesn't mean it was optimal either.
Everything I posted above is based on experience and many times. IDK but if I was guessing, I've had it happen maybe 100 times or more over the years, out of maybe, another WAG, 100,000 rounds loaded in those years. Every single time that I can remember, it never happed after the same cases were fireformed. I honestly don't think I've ever had a bad primer with the exception of one that was missing the anvil. I caught that before loading it. I'm probably forgetting something but the idea is the same. Bad primers are super rare and anything that even slightly deadens the fp strike can cause misfires. Count your blessings if you've never had it happen yet but it probably will, sooner or later. Oh yeah, once the primer is hit once but doesn't fire, it's not impossible but it's far more likely for it to never fire. I've had those go both ways. If ya think about it though, it'd be hard to shatter what's already broken, speaking of the compound in the primer. It'd be a frustrating test but it'd be interesting to group those misfired primers on target..at least the ones that will go off when hit again, and see how bad they'd shoot. Not practical but it'd be interesting if ya could do it.
It's more common on wildcats and cartridges where you are relying on bullet jam to hold it against the bolt, than on anything standard. I've had it quite a bit on different actions when fireforming my 30 Major. The brass runs short and it probably worsens that issue if the shoulder gets distorted a bit while necking it up. I've learned to not even try hard primers while fireforming for it. It's frustrating but it'll tell on you if you flinch on a misfire. I've done it bad enough I just had to stop and laugh at how bad I flinched. Other times, solid as a rock. Lol!
Sometimes it takes a little digging to sort things out. Go for the simple stuff before making a federal case out of it. KISS!! 
