I have 2 file cabinets full of them. I also include the test target.
When I make a log entry I put in:
Case brand
Primer brand and type and lot number
Powder brand as well as the lot number of the can
Bullet brand and type and weight
Trim length of case
Seating depth for jump distance on each particular barrel
Time and Date of test firing
Weather: Temp, humidity, wind speed and direction
Elevation
And of course the scope and magnifications used for various distances
If it's a wildcat cartridge I also put in whatever I did for fire forming the brass
If I neck size only (some cases I do, some I FL resize) then that is noted as well
Basically I try to include all details for each and every rifle/load. When you start gettin old and forgetful, you will pat yourself on the back for having the good sense to write all that crap down. You are on your way to having a pretty good assortment of firearms kiddo. When you start loading for 1/16th the firearms I load for, you will be thanking yourself for that log..