i think lilja is responding to things like the Tubb coated bullets smoothing out the bore of the barrel. It's not possible for the barrel maker to address kreiger's point, which is that the (hopefully) very fine marks from the reamer cutting laterally is what get smoothed out. obviously, those marks from the reamer weren't on the surface of the bore when it left the maker.
sure but you'd have to clean it a lot harder
because a lot more copper would have built up.
i'm not a metallurgist, but I've looked through my share of borescopes and my understanding is copper seems to adhere to copper. I looked through a scope 2 months ago when I was getting my match rifle rebarreled. my old barrel had about 1700 rounds on it and I usually get about 2000 out of them. there were some copper streaks clearly visible in a couple areas, but i was surprised how little copper was there. I expected a lot more. Anyway, if copper generally adhered to steel, why wouldn't the entire barrel be copper coated?
My understanding is the copper in the bore is initially deposited on steel from being suspended in the gas, not from being scraped off the jacket as the bullet rides down the tube. i further believe it got in the gas in the first place from the tooling marks left by the reamer in the throat and especially on the beginning of the lands where they are sloped. Once these marks are smoothed out, my barrels don't seem to copper foul until they start to get that "dry lakebed" crackled surface in the throat. After that point, my extreme spreads usually jump to double digits and my SDs creep up from the 1-4 FPS range to 6-9 FPS.
So once the copper is on the steel, it will continue to build up. Usually, when my barrels are near end of life and start to perform poorly, i will give them one really good cleaning to get all the copper out and that seems to get 100-200 more rounds of useful life out of them, but it's a PITA
sure but you'd have to clean it a lot harder
because a lot more copper would have built up. i'm not a metallurgist, but I've looked through my share of borescopes and my understanding is copper seems to adhere to copper. I looked through a scope 2 months ago when I was getting my match rifle rebarreled. my old barrel had about 1700 rounds on it and I usually get about 2000 out of them. there were some copper streaks clearly visible in a couple areas, but i was surprised how little copper was there. I expected a lot more. Anyway, if copper generally adhered to steel, why wouldn't the entire barrel be copper coated?
My understanding is the copper in the bore is initially deposited on steel from being suspended in the gas, not from being scraped off the jacket as the bullet rides down the tube. i further believe it got in the gas in the first place from the tooling marks left by the reamer in the throat and especially on the beginning of the lands where they are sloped. Once these marks are smoothed out, my barrels don't seem to copper foul until they start to get that "dry lakebed" crackled surface in the throat. After that point, my extreme spreads usually jump to double digits and my SDs creep up from the 1-4 FPS range to 6-9 FPS.
So once the copper is on the steel, it will continue to build up. Usually, when my barrels are near end of life and start to perform poorly, i will give them one really good cleaning to get all the copper out and that seems to get 100-200 more rounds of useful life out of them, but it's a PITA
