+1 on flags
I have been shooting/reloading again for the past 4 years after a 15 year break. I am constantly trying to better tune to achieve smaller groups. I went to my first BR competition this spring and just watch and asked questions. My groups best almost always had more horizontal than vertical. I could really prove this to myself when I back out and shot the same loads at 300 yds. Seeing everyone read the flags (or not) in some rough conditions made me a believer. Before if the wind was blowing more than 10 mph, I just stayed home.
I started only using three wood stakes with 30" of orange construction tape, but I was immediate able to again almost 0.2" (0.5 to 0.3") on my aggs at 100 yds. I am still learning the art of trying to watch the flags with one eye and the target with the other eye at the same time. I am going to buy or build a set of flags but I need to go to another BR match just to look at different flag designs.
Try a crude set of flags as I did. I bet money, your groups will reduce.
Luck, tiny