I don’t have any pet loads or info on 243. But to answer your chronograph question, I’ve loaded for years without one (about 4) but one day I decided to buy one and it really helps add more info. I got the chrono beta just a cheaper 100$ one and started shooting over it when doing load development and it really showed me some interesting things. I was able to see the speeds that fliers went which was usually vastly different. I even had some loads that were 120fps different than what the reloading book said