FinStabilized

Very interesting, thanks for digging that up. On the contrary, I am more concerned with how theoretically other people are taking them. As you say, multiple hits is a real combat situation (as well as opposite), but the problem I see is that it seems as everyone in this thread as well as the other communities I have seen quote these tests, are taking them as face value indications of in-vaccuum performance and not as you indicated here. For example, the PDF that can be found of these calls them the "rosetta stone" of gun performance because it ostensably solves inconsistencies between various nations gun testing methods etc. Except it could not do that, especially given the lack of verification and detail we have. Gun test data and field testing we have is the better baseline. While combat is a different thing entirely, the baseline still serves to inform. For example, if the IS2 test used the single penetrating hit as the lower limit velocity and published that result, it would give an impression of the combat performance of the tank that is not accurate. The fact that we know the tank was penetrated at the weld seam is indicatcative of both the point your making and the point I am making. Is2s in combat could be penetrated through said seam, but we would be wrong to reduce the general effectivenss of the glacis plate compared to the predictated performance we might assume from ballistic science and testing because that generlization is still entirely valid based on the other 4 hits on that armor (non of which made it through, exactly like we would expect). So I entirely agree that neither is incorrect, but it I think its important to discuss which is which in this regard, especially since we lack important details.

Alright, so if it cannot penetrate 90mm at 60 degrees, how is it going to go through 100mm or more? What seems more likely to me is that: -the details of the tests in the notebook are not entirely accurate. Unfortunatley we dont have the actual documentation to tell for certain. -the details are lacking and there are special reasons for the success. This seems highly likely. How many M-47s did the Yugoslavian goverment want to use to test these guns? Was the tank already heavily shot up? Did more than one tank get used? Were all of the hits fair hits? For example a low velocity penetration near another penetration or perhaps near the mg port could explain a scewed 50% probability. The hit on the above IS2 demonstrates precisely why we should take the results here with a large grain of salt. 4 hits bounced off and then one makes it through due to where it hit, etc. I find anything along these lines more likely than the 88mm KwK43 penetrating enormously more armor than other data and ballistic science would suggest is possible.

This? Because it hit at a weld joint and that explains the results. As you can see none of the other hits penetrated.

Which Soviet data? Because I actually find it very hard to make sense of many of the results in these tests. One that is mentioned is the m47. Things penetrate according to the tests that simply don't make sense. Low hardness and cast armor doesn't explain it. The protection values for the glacis should be far far in excess of any margin for error on something like the pak43 being able to penetrate it. The difference in limit velocity between 200-350bhn is very small, and the largest differences are only seen when the armor is significantly overmatched.

Oh I am not expecting anything out of anyone. I know little of Serbia and I do not have really any expectations regarding anyones desire or ability to find these documents etc. My only concern was trying to find out why everyone on the internet is taking them at face value when there is very little to go on. I see them quoted every so often as if they are established historical record.

Who was the person who was involved in the tests? How was the notebook obtained? This leaves many questions about how much the information in these tests can be relied on. Is the person who owned the notebook still around to elaborate etc? Are there any other sources that corroborate that these tests even took place? I am not trying to be unreasonably skeptical here and I am assuming everyone is acting in good faith, but I do not think we should take these at face value unless we have the original documents. The devil is in the details of things like this. There could be tons of information in the original documents that completely changes our understanding of them etc. Even small omissions or mis-rememberings could have rather large ramifications. Do we have pictures of the notebook? Note: I just now found the part mentioning the original source. So this is based on information from unnamed persons and documents which apparently are not officially declassifed. That is not much to go on.

Is there any offical documentation for these tests? I appreciate the posting but these have been on the internet now for well over a decade but I have not every been able to find any proof of their existence. I have never seen another historian quote from them, or seen any pictures of the documents.

The ones that say navy criterion. All 3 versions of terminal ballistics states Navy. I only have the 1948 copy of TM1907, which is the only document that indicates that the "protection criterion" was also involved. I found another document that shows both Army and Navy ballistic limits as separate values, with the Navy ones matching the charts in terminal ballistics and other documents that indicate Navy. I think 1907 is in error or perhaps was just restating all of the criterion academically. But I posted it here to see if anyone else has data on this. Perhaps even the orginal tests for at least one of the ammo types.

The issue is that the criteria are contradictory.

Terminal Ballistic Data volumes 2 and 3 both indicate the United States penetration charts are for Navy Criterion. Volume 3 has "Navy Criterion" stamped above every chart, and the desriptions of penetration in both are in line with Navy Criterion. TM-1907, which appears to contain the exact same charts, lists an entirely different criterion that sounds like Army Criterion.