I have the same round as the one with the GMCS bullet. I cannot claim that I know it is factory, but I will make a couple of observations for what it is worth.
Firstly, the weight of my cartridge is basically the same as Lew’s - it weighs 167.4 grains measured on a properly zeroed RCBS electronic scale. The bullet ogive is the same - more pointed than some RN FMJ bullets. There are no signs that the case has ever been fired. We have discussed those signs recently and they need not be repeated here. The neck seal, a nice shade of reddish purple is identical to the color of the neck seal on a Wollersdorf-headstamped 7.65 mm Browning (.32 Auto) cartridge I have with a 1922 headstamp, but which I consider to be loaded much later than that. I have an early specimen with CN bullet and no seals in the 32 with the same headstamp, and that one is probably more contemproary to the 1922 headstamp date than the one I am using here for comparison. The .32 is also with a GMCS bullet. By the way, on the 9mm the reddish-purple mouth seal, although it is hard to tell in Lew’s picture, on my specimen clearly overlaps the top of the case mouth, so it is not just a bullet with a neck seal pulled and put into another case. The seal was applied after the bullet was seated.
My cartridge was acquired from a box of many different 9mms at a show, at a modest price, not more than a dollar, as I recall. No motive there for faking. Further, because of the questions they raise, their value is probably not much higher than that of the original 9mm Mauser specimens.
Regarding the slight bulge in the case from seating the bullet, you see plenty of brand new factory ammo with such a bulge, sometimes very visible and almost all the way around the case. These bulges usually are like these Austrian 9mm Para with the 9 x 25 Mauser-style headstamp, only visible on one side of the case. The bulge, as everyone knows is from the combination of the bullet diameter and the inside diameter of the sized, ready-to-load case. Even with new ammo, sometimes the bullet is big enough to make such a bulge. It is not a sign of poor quality or anything wrong. I am not even sure how much thicker the case would be after shortening even a full 6mm from 9mm Mauser to 9mm Parabellum, as it still is no where near the web of the case, where it really starts to thicken. It may be thicker or it may not - I simply don’t know. These cases would need to be slightly small in the inside diameter since they show no stab, roll or taper crimp. The bullet is a friction fit, judging from my own specimen.
I consider the load I have to be factory - that is, at the least, an arsenal shortening of a 9mm Mauser case and loading as 9mm Para for whatever reason. Perhaps a surplus of cases for the 9 x 25 or a critical shortage of cases for the 9 x 19. Maybe even nothing more than a clean up of left over components at the factory after WWII. Again, I don’t know. This is one of those loads that could be a dingbat, but everything I know about ammo, as little as that is, points to this being a professional and quantity (not done in a tiny amount) conversion at the least, and perhaps even original 9mm Para cases with the same headstamp as the 9mm Mauser ones. The same basic headstamp, remember, was used on 8 x 56R rounds for the Steyr 95 rifle. (I didn’t say the same bunter, so please, no one read that into my statement). I have seen at least five, perhaps six of this identical round. However it was loaded, my gut feeling is that it is an “original” cartridge, perhaps loaded later than the headstamp date would indicate (maybe even after WWII), regardless of the original length of the case be it made in 19mm or shortened from 9 x 25mm.
I cannot comment on the ones with CN bullet - I have never seen them anywhere before.