Was not factory ammo, was fine tuned handloads, and I'm not an average joe shooter either, I am a LR hunter/shooter so I pay attention to detail and am quite familiar with shooting MOA or less at extended ranges, 400 yards isn't even that far...I had a timney trigger in it set to 1.5lbs, 6-18x leupold w/target knobs, leupold rings/base. Was a solid set up...
With all that said, I've never seen such a swing in accuracy like that with something that shot so good at 100 yards, then go to hel in a hand basket at 400. It was done repeatedly at 400 as well, and the end result was the same, $hitty everytime.
Take my rem 700s for example, everyone when they shoot 1/2 MOA at 100, you can expect them to hold MOA out to around 600 yards off a rest or bipod/prone in good conditions without much of a problem. Its not that hard to hold MOA for 3 shots with a well tuned rifle/load in good conditions with a rest, especially at 400 yards...Like I said, worst case scenario they should have been doing was 1 MOA, and they were still twice that size at 2 MOA. There was no wind, groups were always BIG triangles, no flyers. Groups were always cloverleafs at 100 yards or 1/2" triangles with low ES numbers.
I'm not your average "ding dong" with a rifle shooting at long range. Been doing it for a while now...