I do. I started out by simply recording pet loads that worked really well for me. Since then, my method has evolved a little bit. I still have a separate list of pet loads I use for each caliber, but I also have a separate journal I keep with notes on performance, etc. I bought a hard-bound journal, divided the pages evenly, and put a tab on the first page of each section. Each section is dedicated to a cartridge that I reload. When I go out to shoot, I just flip that book open to the right section and take notes on which rifle I'm using, weather conditions, and how everything performs. It makes load development much easier, when you don't have to scratch your head and try to remember what you did several weeks ago.