I always strip the bolt on a new rifle I am doing load development. It takes me a couple minutes to pull the ejector and firing pin. I leave the ejector out until I am done with load development. For 2 different measurements: First one is to establish C.O.L.- where the ogive touches the lands. It is the most accurate and repeatable way to measure this.
Second to set shoulder bump on my size die. Some new brass needs the shoulder set back a bit, and once fired it may not need setting back for 3 or 4 firings. Your own chamber is the most accurate measuring device you have. This will give you accurate ammo, without working the brass too much. I often see advice to "bump the shoulder .002" this is an arbitrary measurement not based on your chamber and length of your brass.
Alex Wheeler has the videos posted on his site, he makes no money from them, and he knows something about making guns shoot.