Not sure pronghorns qualify as big game, but...
488 measured and observed. Prone, bipod, custom long heavy M700 in 25/06. 115 gr. pill hand load, Weaver 4-16x, Leica laser'd, no cross, good light.
All went as intended, not a trophy but a nice buck. Long range game tastes better...
Seems to me most long range fellers know their rifles, optics and loads very, very well. Also, most will do noticeably better than 1 MOA. Never met a real long range hunter that wasn't a dedicated and ethical practitioner. Its a discipline.
I'm no seasoned 1000 yard artist and I own nothing big and fancy but if you step within that 500 yard mark, conditions permitting, I'll put yer *** in my meatlocker every time