OH. You have found out that most of shooting is mental, not physical once you have your technique and load worked out. If you want to improve your hold, and stance to shoot small groups, at any distance, always practice shooting at longer distance. Then, when you go back to the shorter range, it isn't the kind of "IMPOSSIBLE CHALLENGE" you thought it was.
I use this same strategy to teach students how to shoot handguns accurately at what many consider long range. They think I am nuts when I put targets out at twice the range, and ask them to shoot those targets. There is a method to the madness, but my students often don't figure it out until they see how much better they are shooting at what they USED to THINK was a long range for their handguns. You would join me, and some of my students laughing at how big an improvement in their scores takes place without only a few hours of practice. :hatsoff:
I have friends who routinely put metallic silhouette targets out at 150 yards, and shoot them, there, to practice to shoot the same targets during a match at 100 yds. This with small bore rifles. They usually clean the 50 yd. targets, when they never came close before I "abused" their minds. :blah: :haha: :shocked2: :hmm: :thumbsup: