I keep every target and corresponding data I've done in load development . I started out with one binder for every rifle I load for .
The binder would start with a general data page of every bullet I load and the jam BTO measurement for each .
Then the desired CBTD ( case headspace ) measurement .
Dope of the reticle using the best load I've chosen .
Round count and dates
Next was the data it self which was separated by powders . I'd have tabs that would have the specific powder . Once you turn to those tabs I'd then have that powder divided into bullet types then weights and I have every target and data sheet I've ever worked up . OK not "every" one of them but most of my rifle data I have and a good bit of my hand gun data .
I to then have index cards with all my best loads in a index card box separated by cartridge then rifle for quick references .
This was my Load data sheet , It's now just one data area with a large lower section for notes for each charge increment .
Targets like this or similar so the data sheet and target go in a binder well together .
A lot of guys use a PDF format or the like . I'm not computer savey enough to do that . Nor do I trust electronics to store my life time of data only to see it disappear in a second when I get the blue screen of death . I have three dead computers in my basement with my kids pictures and videos on I can no longer see but won't throw them out because I know that data is in there somewhere . Yeah yeah I can print out the data sheets or save them on a thumb drive . The thing is , It's already written down from the range trip . No need to reenter all that data , scan targets again . Three hole punch and toss in the correct binder and I'm done .
Over the years I've had to go back and look through my data several times for a variety of reasons . Once I had to pull all my targets for a specific rifle to find a problem I never saw when looking at them one at a time weeks apart .
Hell a couple months ago I was going to work up a new load and got already to start loading but thought , lets take a look and see If I've worked this up before . Sure enough I had already worked up the exact same components in the same rifle like 7 years earlier . You do this long enough you're bound to repeat your self if you're not careful lol .