Decent outing overall. Here is one of the things I use as a tool to help diagnose peoples shooting.
You were probably correct where the guy with the magnum was throwing you off. It probably added to your assessment of anticipating recoil. You may also have a little too much finger on the trigger.
This is why we go to the range. We find things out good and bad and we take what we learn and go back to better our skills. Learning how to focus and not be bothered by the guy next to you will come in time too. Keep at it. Marksmanship is a perishable skill. The more often you go, the better your muscle memory and other skills will become and your shot placement will reflect that.
Remember that there are many factors to good marksmanship. Take your time. Rushing shots also seds them where we don't want them to go. When you recognize yourself starting to rush, force yourself to slow down. Happens to all of us. Aim fast, squeeze slow. Let the snap of the recoil "surprise" you. Remember to breathe normally. When you are lined up on target, exhale half way and hold. Squeeze the trigger and resume breathing normally after the shot. Repeat. And don't be too hard on yourself. You'll get better and it's suppose to be enjoyable