Ive shot out of an M14 Match rifle and an M1A lots of different ammo. 173gr FMJBT Match white box ammo, 168 SMK White box match, 173gr FMJBT Brown Box Special Ball, 175gr SMK M118 LR and M80 Ball. The best Ive seen was 168 white box match, but the occasional lot of Special ball would do close to 1 MOA.
M80 Ball would do about 3 MOA. At 700 yards that would equate to approximately a 21" group as far as mechanical accuracy is concerned. Plenty good enough for a bunker, meybe not so good for pinpoint accuracy.

I've shot my personal M1A at 1000 yards at Ft Gordon and won a couple matches with it, but don't consider them to be good 1000 yard guns. I have also heard that you could bend the op rod, but I've never seen it, even when you would hear of some knucklehead using 4350 and 190's or some such foolishness.

When people face the possibility of freezing or starving there is little chance they are going to listen to unfounded claims of climate doomsday from a bunch of ultra-rich yacht sailing private jet-setting carbon-spewing hypocrite elites