Greeting fellow Great Falls member! You have gotten excellent advice but you might want to slow down because it is a lot of information to process. "I" normally follow or a modified version of the barrel manufacturer's barrel break-in procedure and do not worry about groups until "I" have gone through a couple of boxes of ammo. For load development, once I get "my" velocity goal for the bullet I intend to use, I play with the seating depth (some might do the opposite). While the magazine clearance is a good starting point, you will need to find the best compromise between CBTO and COAL as well as a compromise in accuracy and velocity that your rifle likes. Sometimes there are extreme seating depths that a particular rifle likes. For instance, I wanted to shoot the 215 Berger on my .300 WSM and determined to make it work
; .160" off the lands was the magic depth for my rifle. But sometimes a particular rifle just does like a certain load combination ... ahh, the beauty and fun of custom reloading.
You got this, keep us posted and be safe. Cheers!
Ed
ADDED:
PM'd you.