Don't overlook the fact that the machinegunners go through a lot of our favorite milsurp ammo in a short time. Remember the conversion kits for the Browning MGs in whatever caliber was inexpensive and available at the time? I don't begrudge them - I envy them!
I sure wish I'd had the cash to buy a tractor trailer load of 8X57 and .308 when it was comparatively cheap, and a place to store it!