Valkas, Very useful information. The 7.5g (115gr) bullet was only used by the UK (and the British Commonwealth), Finland and Italy prior to or during WWII, except for some WRA/WCC contracts for Central and South America, as far as I can tell. The US produced 115gr ammunition for the UK (and perhaps others) during WWII. None of this ammunition has, as far as I know, red case mouth seals. Finnish WWII cases can be found with red casemouth seals, but these were apparently refurbished after WWII.
So, almost certainly your bullets are post WWII production.
Based on the GM plated steel jacket, and the ogive, and where they were found, my guess is that they are Russian commerical loads. Various Russian manufacturers have sold commercially 9mm Luger ammunition with 115gr bullets and GM plated steel cases and red case mouth seals in the US for quite a few years. I suspect these have been available in East Europe for at least as long.
Another possibility is Czech ammunition. I have some examples of S&B and PS made ammunition post-WWII that has GM plated steel jacket, 115gr bullets. Bulgaria, Romania and Hungary have also produced GM plated steel jacket bullets with red cms, but my examples of these all have 124gr bullets. Still, it is possible that they produced 115gr bullets which became popular loads post-WWII
Another chance is Finnish post war 9mm ammunition, but, to my eye, these have a somewhate more blunt bullet ogive. Most Swedish 9mm with a red cms is loaded with a 108gr bullet.
This is my best guess or guesses, but you can be very confident that these are post-WWII bullets.
Others probably have additional information, particularly on who loaded 115gr bullets post-WWII (or even pre-WWII)