Old school. I keep notes in a wire bound note book. Keep it in the box I bring my targets, ammo, stapler and crap. It's really helped a few times with the 'Ol "Now....what the heck was I loading these at for this particular gun ?" type of thing, plus I feel all official and stuff when I break out the pen and start writing down the temperature, wind, weather,light conditions and so forth at the start of a session. OAL/bullet combos for a particular pistol are a biggy. The Ruger Lightweight for example just doesn't care, it'll shoot stuff you pick up outta the trash. The Colt 5 inch on the other hand.....how far did I have to push those Blue 147's in so the thing would run?