Re: .38 special priming
I reloaded my first .38 Special ammo in 1969. My experience tells me to disregard primer "below flush dimensions". I don't think I've had a miss fire due to poorly seated primers in many years, and I just make sure the primer is all the way to the bottom of the pocket. I also use a ram prime after trying most different priming methods and the feel is superior, to me. So, just run the primers all the way in and don't worry (take a primer apart, carefully and see how it works. The anvil needs to be solid, stationary, against the bottom of the pocket so the cup can be distorted by the firing pin and crush the compound between the anvil and cup.)
I had one instance where I had primer problems when I seated them normally, and that was with a striker fired 9mm handgun. I wound up seating the primers (Winchester and CCI) to the bottom of the pocket, then adding a bit of "pre load". The problem went away and have fired mebbe 400 rounds without a misfire...
My Anchor is holding fast.