For those not into 7.9, but interested why these are great headstamps, I will try to provide a more complete answer. The first thing we must know is what would standard Polte headstamps of the period look like. Below are some examples with a brief explanation of why they are what they are. These would apply to most German 7.9 headstamps of the period, except that the factory designator would consist of other letters or “P” followed by a number, rather than just standing alone as it does on pre-1941 Polte rounds:
P S* 10 39 Polte, Werk Magdeburg; 72% brass alloy case; lot number 10 (case lot only, nothing to do with the loading lot); case manufactured in 1939.
aux S* 24 42 The same as above, except the new code for Polte Werk Magdeburg, “aux.”
aux St 1 41 The same again, except with “St” for unimproved steel case.
aux St+ 3 43 Now showing the plus mark after the steel-case identifier to
indicate that the case is the improved pattern with strength web at the base.
aux - St+ 4 45 Now showing a dash after the factory code to indicate that the case has a single flash hole.
The above are made up headstamps. I don’t know off hand if the lot numbers exist as shown. They were merely done for example, and I didn’t want to run downstairs just to make them accurate as to lot number, since it is irrelevent to what I am trying to get across.
Now that you have seen what the standard headstamps looked like, you can appreciate the fantastic headstamps Lew showed, missing all sorts of information from the bunters, adding the word Probe and a number indicating a series of experiments, etc. etc. In short, these headstamps are not the norm; in fact, they are all incredibly rare. That makes them much more valuable financially speaking, and of great interest to the advanced 7.9 x 57mm collector. I wish I had even one of them in my collection of 12,000+ rounds of this caliber.
For another example, it would be like finding a WWII Frankford Arsenal .30-06 cartridge with a headstamp like “FA Experiment #8 42.” No, to my knowledge, that does NOT exist. Again, just an illustration of what I am talking about.
Hope this clarifies the subject beyond just “experimental” which while true in these headstamps shown by Lew, is one of the two or three most over-used words in the cartridge collector’s vocabulary.