I recently came into a mixed batch of 7.92 steel case with a range of headstamps. I assume the blue primer seal is SmE, and the green seal is lead-core ball, but what about the primers with the full blue wash? Are any of these headstamps anything interesting?
In France the entire blue primers has been sold under the name “arctic” (i think fantasy name)
the real purpose is for protect the primer because is not oxidizing proof, but I heard that it cause problems in machines guns (firing pin malfunction due to increased amount of “crap” in the firing pin hole)
The portion about the full-coverage primer seal gumming up firing pin holes is the accurate answer, I believe. I used to use a marking pen on the entire base of my .45 loads, to ease sorting out brass at the range from those cases belonging to other shooters, I stopped the practice when the firing pin on one of my .45s was “glued” into a far forward position when dry-fired (nothing in the chamber to halt is advance) which could have caused a whopper of a malfunction.
To the lot numbers of your pictures they are all SmE rounds with a primer 88, primer 30/40 blue and primer 30/40.
Until 1943 the primer 30/40 was only used in practice ammunition.
They started to protect the primer 30/40 in life ammunition with a complete protection against rust. They found out later that this protection was not necessary.
They skipped it after a couple of months.
It was not only the SmE round but also sS and SmK, green and red.
The air force the new primer 43 was also protected this way.