OK, I'll throw my hat in the ring. It really wasn't as bad as I though it might be.
First I shot a couple from the bench, rested, @ 65 yards to confirm the rifle zero. That's my standard yard stick here in Jackland since it's where my bench is. On the nutz I moved on to the first standing shot I've taken seriously in a while. This is big to reference the target lay out for later. I don't use the fancy paper targets rich folk have got.
First 5 shots standing, using a loop sling, 223 AR, 3x9 scope, 75yds.
No sighter shots after 2 confirming shots from the bench.
Right away I think I've diagnosed low shots from a rifle with a confirmed zero. It's a lack of follow through. Probably most, may be not, but it's my biggest challenge I've identified right away. It's exactly like shooting a bow. Follow through = good shots. Dropping your arm on the shot = a sure low shot.
Don't laugh at my scale lines. I marked those using a tree branch. It's a 12"x12" piece of AR500 steel.