>>64103072
Because it actually isn't.
7.62x54mmR reaches longer than 5.56x45mm NATO, but 7.62x51mm NATO can reach out far enough to match anyway, however this doesn't really matter that much, because the reality of these engagements is that they were sporadic harassing fire which typically is already outside the practical range of the PKMs in question anyway.
You're looking at U.S Troops walking into very specific situations where they start receiving fire, but this fire is from SO fucking far away that it's incredibly difficult for the attackers to actually score any hits at all, and it's more just generally hitting around them (and at low velocity, after all that airtime).
Being so far away, obviously 5.56mm doesn't reach back in response, but neither does 7.62mm NATO, because this is really a matter of fire past realistic and effective infantry engagements, the Grunts and Durkas are often not even able to see each other with the naked eye.
G.I's aren't being horribly suppressed and absolutely helpless in this situation, it's more like they are being inconvenienced and annoyed because it's just kinda dangerous, they COULD get injured here, but they virtually never are. They can't adequately respond to the fire, but the incoming fire isn't even adequate either, and it's not the kind of tactics you'd expect from peer or near-peer adversaries either, this is very much an asymmetric thing, and which doesn't work either.
This is a lot like when WW1 era infantry rifles had sights ranging out to 2000m with the intent that this would be used for Harassing Fire, something which was virtually never useful (for small arms, anyway), and U.S brass are acting like this is A), completely unforeseen and shocking, and B), like this is something of actual consequence. Possibly in return for money.
