I was issued a Surgeon Rifle PSR in .338 Lapua. I followed Kreiger Barrels break in procedure to a tee. The barrel had a spot at the muzzle that was holding a lot of molten copper that was clearly visible to the naked eye. As the shoot and clean process evolved, the spot at the muzzle collected less and less copper fouling. I can now shoot 40-50 rounds in between cleaning with no loss of accuracy until the 50 plus round mark. The area that was grabbing the copper is now no longer holding fouling and the rifle will hold 1/4 MOA if I do my job. I experienced much the same breaking in a .408 following Federson' s and EDM procedure for break in. A little different method, but same results. Rifle cleans up in a few patches, accuracy improved after 100 rounds. Just a couple of hands on experiences with break in of a high dollar rifle barrel. I do not break in Chrome lined or production barrels. Just shoot them to junk and swap them out.