EOD - I thought of that myself. I know the inert blue-tip rounds we have seen from exhibitions (in my case, only 9 x 18 mm), representing proof loads, evidently only represent commercial proving procedures, despite at least one having a purely military headstamp.
When you pulled that bullet, did you weigh the powder charge. I know it won’t tell us much, as the three Russian Tokarev rounds I just pulled apart to check standard bullets for weight and length and shape all had similar, but different powder in them. It seems these days, powders are more consistent in Russia. I know that a lot of different makes of Makarov ammunition are loaded with P-125 powder.
Still, if I knew the powder charge of the yellow tip round, I would pull apart a few more Tokarevs and weigh their charges, even though again, it wouldn’t prove much without knowing the exact powders used. Unfortunately, I did not think to save the charges from those already pulled.
The other question is the steel-core, longer, boat-tailed bullet. Since it is the same weight as the standard flat base, lead-core (?) bullet, the only way it, of itself, would boast pressures is through more protrusion into the powder cavity, reducing burning space. I am not sure it would be enough to raise pressures to proof-load levels. Along the same question, had they made the longer bullet with a lead core, it would weigh more and that would be a second means to boast pressures - however, they did not, so…?
Just some idle observations.