In the real world US military the 308 is limited to DMRs in regular infantry units, you’ll have a very few, select infantry units that will carry the .300 as a DMR. When you move to sniper units the .50 is the workhorse and Ive only seen the Lapua fielded by select units. Can’t recall any sniper/recon units carrying the .300. Now there’s always teams that are testing or doing whatever and you can see all kinds of weird shit in regular units but it’s usually only one or two for short development and testing periods.
Of course when you move to your JSOC, spec ops, etc. then all bets are off and they get what they want. I’ve never been involved with them though so I hear the rumors as anyone else.
I will say, I had a roommate once who left one night with a set of flippers, mask, etc. (we were nowear near an ocean) and jump gear. I didn’t ask questions, he came back a few days later looking like absolute shit.