I keep a reloading ledger and record every batch of ammo I load. Each entry starts with the date and includes; Powder type and weight, bullet type and weight, bullet seating depth (COL), primer, cases, and comments like; new load, established accurate load, shoots good in gun X but not in gun Y, etc. I also mark the ammo box with the same basic info.
I maintain a log for each gun I own. Every time the gun is fired, any sight / scope adjustments, cleaning, or maintenance of any type is done, it gets logged. I work up loads for each gun then log the results of the chronograph and group size. My data includes shooting conditions (windy, rainy, hot, etc), number of rounds fired, and a cross reference to my load data for recipes.
I know this sounds anal but I have quite a few rifles and handguns to keep track of. I also have multiple guns in some calibers and they don't all like the same loads. My rifles all have an Eagle cheekpad with a zipper pouch where I store the logs and ballistics charts. The handguns have storage boxes where I keep the logs. I admit, this is an overkill for most shooters.
