I've found those things you've done to improve has also worked for me real well too, even though I'm not a competitive shooter. But I do compete against my own numbers.
I've learned a lot along the way since I started precision reloading. Some things make a dramatic difference, like with sorting primers; other things, like annealing or cleaning primer pockets after every firing. . . not so much.
A couple other things that has really helped my "scores" is getting really consistent neck tension and consistent seating depths. I found the best way to get consistent seating depths is by sorting my bullets by BTO where the comparator I use touches the ogive at the same place as my seating pin in my seating die. Since I jump my bullets .010" or greater, the typical BTO measurement is of no consequence. I guess along with that too is I use an arbor press and a Wilson InLine Seating Die that give me a good feel during seating.
Since I typically buy powder by the 8 lbs., I've learned to keep track of the moisture content as over time it changes and those changes can have significant affect. Living in a very dry climate, as I do, it's easy for the powders to loose some moisture over time (it can be just the opposite for those living is very humid climate). So, every time while I'm charging up a bunch of cases, I take readings of the humidity inside the bottle of powder using a Kestrel Drop and record the final reading at the end of my session. I've had to make changes in my seating depths when I see a change in just a few percentage points.
