Lazy Eyed Sniper pretty much said it in a nutshell. When I do a barrel break-in, I'll first clean that barrel before I even fire off the first shot. This will get out any leftover metals left behind by the Manufacturer during the build process. Also lets me know that the barrel is clear of any obstructions. I'll now mount scope and do either a simple bore sight or a lazer bore sight to help with bullet alignment. When I get out to where I'm gonna shoot, I load 1(one) single round into magazine well and chamber round. This will be my rifle's test shot at a target. Not to see if I'm getting on paper, but for Myself and Rifle's Safety Check. If goes well, I'll reclean barrel and do a recheck on rifle to make sure all screws are still tight, bolt still works properly, and load only a couple rounds into magazine-well to check for consistant feed. I'll FIRE OF A SLOW 2 rounds, this time to see the bullets print on paper and adjust scope, and do a reclean and let barrel cool off for 20 to 30 minutes or more. I do this combination, of slowly shooting 2 times and cleaning thoroughly, until I'm through 20 shells. This also takes probably 8 hours or more to do. Now, I'm ready to try what loads the rifle likes. If by chance the rifle likes what you're already shooting, it makes it simpler, but if rifle is printing all over paper, then you need to experiment with other ammo brands and loads to find that right combination, or at least the best you can find in Factory loads for the tightest grouping, if you don't reload. However, also remember if you use cheaper, low-costing scope/rings on a high recoil rifle, and it just doesn't want to stay on target, it may not be the ammo you're shooting, but the equipment you're shooting with. If by chance I get/use a tube fed/ lever action or semi-auto rifle, I'll go through the same shoot/clean procecure, but I'll be looking at other possible problems with lever action binding up, shells not feeding properly from tube, or jams with semi-auto bolt.
Del