I have long held the belief that a lot of IA Gernaails actually don't understand the difference between 7.62x51 and 7.62x39...or atleast don't take appreciable note of it.
Not once have I heard any high ranking brass actually differentiate them when talking to media (even informed defence media with which you can go into depth if you want) and instead they simply clump them both together as "7.62mm calibre".
While it's true that they're both .30cal rounds, there's a world of difference between the two in terms of ballistics...especially as you look to engaging targets beyond 200m.
It's like how 5.56x45 and .22LR are both .22cal but one is a decent combat round and the other is a peashooter.
Oh well, I have stopped worrying about the sardardh that is IA small arms procurement...life's been much more peaceful since