The target tells me what the rifle likes. I have a spiral bound "book" of 3.5 x 5 cards, that are perforated, but not so you have to be careful about accidentally tearing them out. When I am loading at the range, I start a new entry with the day date and time. Although I don not record every single detail of every trial load, I note which rifle, and barrel, what bullet, what powder and if it applies, lot, Seating depths are recorded as the combined length of the stem and cap of my Neilson seater. Powder by measure setting, also noting throwing technique used, since that has changed over time and different techniques yield different weights of powder. When I find a good load I note the temp., humidity, seating depth, and charge by measure setting. I also will note wind conditions and how good the groups looked.
Some time back, I helped a friend fine tune a load for his PPC. Not being a benchrest shooter he arbitrarily changed the load, and lost track of what was needed to make the rifle shoot. We had noted the load by seating depth, charge weight (saved one for him to take apart and weigh when he got home) temperature and humidity. Some time later he told me that he was not getting the accuracy that I had tuned it to, and discussed the changes that he had made, we took another trip to the range. The conditions were more or less identical. I consulted my notes, and loaded up some more of the same. They went into the same tight little low two. Not take notes...you would have to be a fool.
