Experience is a neat teacher. Broke the first Badger barreled gun in with all the hoopla, second one forgot about all the nonsense and just found a proper blackpowder load for it, and away we went. First gun has a new barrel on it already second gun is chugging away just fine.
If a person was really interested in doing a "break in procedure" on a bpcr barrel 4-500 paper patch rounds is likely the best route, plus it should teach you a little bit about proper loading and shooting of a blackpowder cartridge rifle along the way.

the most expensive bullet there is isn't worth a plug nickel if it don't go where its supposed to.
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