Every rifle has its own book. I keep everything that I measure, load, shoot, try, want to try, don't want to try (you get the point) written down in the book. Everything is dated and documented. Each page is a new date so as not to confuse myself. I try to get the little books with small grid paper so I can record my range session hits as to be able to recall them without having to dig through my targets. I also keep my targets. It would drive me nuts if I didn't do this. Life is so hectic as is, I cannot imagine trying to remember specifics for load development from day to day without notes.