This brings up a point I was trying to drive home with a buddy. we had went to the range and shot a bunch 60+ rounds fairly quickly with his hunting rifle (30-06). He was adjusting his zero the whole time trying to center punch the bull.

I told him he needed to let it sit and completely cool then send a round to verify zero. He said why it's zeroed. I told him his cold barrel would shoot quite a bit different then it did after all the shooting he had done his POI was different. He did listen to me and it was off by 2" at 100yrds.