This is the scale I finally got, love it BTW!
https://www.amazon.com/gp/product/B011J88S8M/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1 For head size measurements this is one option... It's not as accurate as a air gauge system, but its fairly close, and with some practice is fairly fast.
http://pelletgage.com/products As for your graph... Your gun between yourself and the prior owner should be "ready to go" in terms of a break in. some where around 1000-1500 shots should be enough. Mark please correct me if I'm wrong. I'll leave the tuning of hammer tension to the expert in this thread. But the big down hill line is you off the regulator. Once you get your hammer tension part worked out, run this string again and watch for a increase in FPS for a shot or two, then for it to fall over the face of the paper. Make a note of the shot number before the increase, that's your max shots per refill. Maybe knock one or two more off that to be safe.
On my BM500x I get between 28 and 30 shots from a 230bar fill. 28 shooting 50gr, 30 shooting 44gr. So here is what I do... Fill to 230bar, checked on both the tank gauge and gun gauge, take (1) "sighter" shot, I do this to make sure the regulator is good to go with the newly filled tank. Then shot 28-30 rounds, stop, refill, sighter shot, back to recording holes in paper. Remember for 75y and 100m BR you can refill as many times as you like during the competition, so it really doesn't matter if you get (10) shots per fill or (100) per fill as long as you know when to refill, i.e. before you come off the regulator!
Here is the cleaning tool I use, cheap and easy, works great!
http://www.mac1airgunshop.com/jl-crown-saver-p/jlcs.htm A good example of what Mark was talking about on cleaning... I have a 22lr with a match LW barrel. The guy I got it from recommends. "Clean the chamber about every 200 rounds. Run a tight dry patch breech to crown ONCE every 2000 rounds. Never use solvents or brushes on my barrel!!!! Shot 50 rounds after you clean it to get in in good working order again."