Jean Pierre - while I am not especially scientifically-minded, and do not know the ins and outs of the copper-crush system (I do understand the basic principle, of course), I do not know why they vary, but the truth is, the holes on all copper-crush test cartridges are not the same, nor are they all located in the same position. As you stated, the French 9mm ones I have have a very small hole, but I have noted that they are found at different heights n the cases. I have three Swedish ones in 9mm, and they have holes of approximately 4.90mm - 4.95mm (they are very hard to measure, and are all located at the same height on the case as each other. The copper pellet for them, one of which I have, measures precisely 9.00mm in diameter and precisely 12.00mm in length.
Ray - I noticed the lack of a flash hole in the aluminum copper-crush round pictured as well. Doesn’t make any sense, does it? I don’t know what these tests were all about. I have six pieces from them in my own collection, all damaged in one way or another. (They were found in a dump in Eastern Germany, I hear, and time has ravaged them, although some of the damage appears to be not related to deterioration while in the ground. It appears that the tests were as much a test of primers and priming systems as of aluminum cases. I have the following:
TJ - Primer intact, but corroded to a point of not knowing material of cup, except that it is not steel. No visible flash hole inside the case.
TL - Primer intact, copper cup, 2 Berdan-type flash holes.
TL - No primer at all. Single, centered Boxer-type flash hole.
TM - No primer cup but a ring of copper proving without doubt that a copper primer cup has rotted out. No visible flash holes.
TM - Primer intact, copper primer cup, single, off-center Berdan-type flash hole.
TN - Primer intact, brass primer cup, 2 Berdan-type flash holes.
It would be interesting to know if those with a primer but no flash holes ever had priming compound in them, and if the Berdan types have an anvil built into the flash hole. It would also be interesting to know if the ones with no visibile flash hole have a thin center at the pocket for some sort of primer burn-through test. It would take a much bigger collection of them than I have to find these things out, and a willingness on someone’s part to section a few of these. With the small number in my own collection, despite their condition, I don’t want to chance destroying any of them tampering in any way with them. I understand that over twenty variations were found.
Perhaps someone with much more knowledge than I can fill us in on some of the reasons for the tests, what the headstamps mean (I have been told that a logical explanation of the “T” is for “Troisdorf,” but I don’t know what that interpretation is based on, and why some “primed” cases do not seem to have any flash holes, especially a pressure-test round that in its other features, looks completely legitimate.
Edited for content - some measurements were wrong or incomplete regarding the Swedish 9mm Pressure-test rounds.