My involvement with this thread will be more to expand on what Lew has written than to provide a definitive answer to most of the questions put forth.
First, my sincere apologies to Lew. He and I, thru email, discussed this at length, and due to time constraints, perhaps on both of us, I did not provide all the information I had, as I did not have time to renew my formal research of the so-called “9 mm Nickl” cartridge. The last day or so, I have found time late at night and early in the morning to do more research in my own files. Most of my research for this cartridge was done from seven to eight years ago, and in my conversations with Lew, I had forgotten some details, including sources for confirmation of some of the information.
That said and out of the way, I would like to point out a couple of things that do, despite initial appearance, have a bearing on the information below on the Nickl pistols and cartridge.
Firstly, the rim diameter on a cartridge made primarily for blow-back operated pistols is generally not critical. Due to the necessity of conpatability with extractors, however, rim thickness and, to some extent, the width and diameter of the extractor groove, and the angle of the extractor-groove bevel can be important. Blowback pistols have been designed that don’t even have an extractor, although it is paramount that they have some substitute feature that allows easy removal of a live cartridge during the unloading process. In firing, the same gas pushing the projectile forward pushes the cartridge case rearward, like a piston, to open the slide. Extraction becomes part of the cycling process of the pistol’s design. The Beretta Minx and Jetfire series of .25 auto pistols are examples of extractorless self-loading pistol designs.
Secondly, becuase of the rim diameters, the 7.65 mm Browning and 9 mm Kurz will often work in pistol magazines of either caliber. I, personally, have fired the 1922 Browning in .380 Auto caliber/9 mm Kurz using a magazine clearly stamped “7.65 mm” at the bottom of one side. I have done the same using .32 ammunition in a CZ 24 .380 pistol using a magazine clearly marked CZ 27, and therefore intended for the .32 (7.65 mm) caliber. In fact, I owned a FN Browning magazine marked “9 m/m” on one side (perhaps with a modifier like "C: for “Court - Short”, a point I simply don’t recall) and 7.65 mm on the opposite side. These were clearly factory markings, both surmounted by “FN” enclosed in an oval.
The reason for this explanation is that there is credible information that the first Nickl Patent pistols of the caliber in question were made purposefully and by design to be easily converted from 9 mm Nickl to 7.65 mm Browning caliber simply by changing the barrel and magazine, and no other component of the pistol. Considering my above comments, it is possible that designing a rebated-rim version of the .380 auto (9 mm Short) cartridge was, in that case, an unnecessary exercise, or “gilding the lily.” It could only be told for sure if one had a Nickl pistol in each caliber, both with the factory-correct magazines, to see how it worked, but the FN and CZ experience with the magazines being basically interchangeable between the two calibers indicates it might have worked satisfactorily. (I am, in no way, implying that every company that ever made both .32 and .380 pistols used a magazine of the same dimensions for both calibers). While I have not seen real documentation for the assertion that the inventor, Josef Nickl, wanted this quick-caliber change feature for his pistol, there are sources that so indicate that it was the reason for the rebated rim. One source is the distinguished ammunition authority and collector Josef Mötz, of Austria. That the cartridge was specifically designed with the rebated rim, and not just an error in specifications (not likely with four different factories having manufactured this cartridge, with at least one of them, the Gustab Genschow company, having made the true .380 Auto cartridge as well) is also mentioned in the book “MAUSER PISTOLEN,” by Weaver, Speed and Schmid, Collector Grade Publications, 2008, pages 120-135 and 155-157.
The above gives reason to believe that perhaps the term “9 mm Nickl” has some legitimacy, in that the rebated rim seems to have been a design change to the 9 mm Browning Short cartridge made for the reason cited above. However, that, and the following information, makes it extremely difficult to explain the reason that the Nickl cartridge is relatively common, while the variations of the true Mauser Nickl Pistols, and the Czechoslovakian prototypes of the Nickl design (for which we have not yet, to our satisfaction, confirmed for which cartridge type they were manufactured, the normal 9 mm short or the rebated rim 9 mm Nickel), are so rare that few of us are ever likely to actually see more than pictures of them, much less ever handle one.
One thing is sure. The older “common knowledge” that the first serial production of this particular Nickl-designed pistol, the Czechoslovakian CZ vz. 1922, which was tested in 1921, contracted for in april 1922 and officially adopted by the Czechoslovakian Armed Forces in June of 1922, was manufactured for the rebated rim originally, and then later had breech-face alterations to take the standard 9 mm Browning Short cartridge, is not correct.
The pistols were adopted and originally manufactured in 9 mm Brownig Short caliber, the cartridge being also designated vz. 22, remaining so-named until past the end of WWII. The earliest-known Czechoslovakian cartridge is dated 1924 and has the vz. 22 cartridge-model designation right on the headstamp. (It is a very scarce cartridge, by the way).
Lew has already pointed out that the “H” headstamped cartridges, made for Rheinisch Metallwaaren’s Düsseldorf facility, with various componets by Ancien Établissements Pieper, of Belgium (AEP) come packed in boxes marked simply “9 mm Kurz,” with no mention of Nickl. It does not appear that AEP ever made the rebated rim version of the 9 mm Short using their own headstamp. Cartridges from Deutsche Werke A.-G of Berlin, came in boxes marked for the Ortgies Pistol and with the caliber marking “.380-9m/m” on the box label. I have no information for packaging of the rebated rim cartridges by Geco or by RMS (the Sömmerda branch of RM).It might be helpful to note that cartridges with the * R.M. * S. headstamp exist, loaded with a CNCS bullet, in the normal 9 mm Kurz rim configuration, and also with the rebated rim, but loaded with a GMCS bullet.
I don’t know of any known box marked specifically for a cartridge designated as “9 mm Nickl.”
Nickl pistol prototypes of Mauser manufacture, by the way, exist in .45 and 9 mm Parabellum calibers, as well as whichever version of the 9 mm Short was actually used.
I have also seen no documentation as to why the CZ vz 22 was marked on the left side “9 mm N.” The problem with taking it for granted that the “N” in this case stands for “Nickl” is that the Czech word for cartridge is “Naboj.” There is also the possibility that in this case, despite following the caliber marking “9 mm” that the “N” does stand for “Nickl” but refers to the pistol being “Nickl Patent.” All conjecture, unfortunately.
Well, these are the important points of all of the various information items I have in my own files for the “9 mm Nickl” cartridge. I have not reviewed the known headstamps and cartridge features, as this information is readily available elsewhere, and this answer to Lew’s opening of this thread is already way too long, I fear.