As a benchrest shooter, I have gone through many barrels in the past 20+ years. I have tried just about every barrel made in the US. I am a believer in a break in process, some are adamantly against it. For the most part, barrel break in laps the throat/leade where the reamer cut it, but does condition the rest of the barrel to be the same.
The amount of break in varies, in my opinion. The premier short range benchrest cartridge, the PPC, doesn't need a lot of work, the case is small, the twist isn't fast, and it goes quickly. But if you shoot long range, and use big cartridges with long bearing surface bullets and fast twist barrels, then the process needs to be done in a slower manner. Take your time, be sure to get all the fouling out before shooting again. Copper fouling will build upon itself and worsen the process. These are my findings based on my experience, others will have other thoughts.
Make no mistake, every barrel maker can make great barrels, but each and every one of them make bad ones too.
BP | Bronze Point | IMR | Improved Military Rifle | PTD | Pointed |
BR | Bench Rest | M | Magnum | RN | Round Nose |
BT | Boat Tail | PL | Power-Lokt | SP | Soft Point |
C | Compressed Charge | PR | Primer | SPCL | Soft Point "Core-Lokt" |
HP | Hollow Point | PSPCL | Pointed Soft Point "Core Lokt" | C.O.L. | Cartridge Overall Length |
PSP | Pointed Soft Point | Spz | Spitzer Point | SBT | Spitzer Boat Tail |
LRN | Lead Round Nose | LWC | Lead Wad Cutter | LSWC | Lead Semi Wad Cutter |
GC | Gas Check |