You do realize most all barrels are contoured after rifling.... right?
As far as I know, and I could be wrong, the blanks are drilled and rifled as a straight, untapered round stock, then final contoured (which is why you can buy uncontoured barrels)
Does anyone ever really contour OR flute a barrel before it has been rifled?! I think you want to have the barrel drilled and rifled, and then indicated on a lathe true to the bore so that the contour and fluting are concentric to the bore.
Ya'll are indeed incorrect, but for different reasons.
McCameron: if you're going by "most", then "most" barrels are hammered these days. Probably by an order of magnitude. Hammered barrels are contoured, and often even CHAMBERED, while in the hammer. Concurrent, not post.
fdkay, you are right some of the time. But the premium makers like to not be turning down their barrels after they spent so much time and energy and money making such a perfect bore. More on that in a sec.
Xander3Zero: Yeah. Lots. You think wrong, but I know what you mean. Keep in mind though that there is FIRST a clean lathe pass made on a piece of rusted-ass rough stock that was just sawed loose from the pile of steel sitting outside in the parking lot. THEN, they'll proceed one of several ways to creating a pilot-bore near the final diameter...but that still has to be reamed or honed and/or hand lapped up to final dimension. At that point, they can first judge a blank's straightness and toss it if the hole wandered too much, and they ALL wander. If it meets spec, THEN they can rough contour and proceed through the rest of the cost.
I'll repeat m'self some here, but..
Krieger, Bartlein--and I am sure others--rough contour their blanks AFTER rough contouring, and BEFORE final honing/reaming of the bore diameter. Some then proceed to a hand lap. And only THEN is the rifling cut.
Ya gotta get a STRAIGHT and consistent diameter hole before you even fuck with rifling. Rifling is EXPENSIVE. As such, any process (like fluting or outside contouring) that might fuck up the bore dimension AFTER $$$ has been spent on rifling is therefore done before that.
At any point along the process, they can toss a blank in the scrap pile without having spent any more money on it.
But for particularly hammered, and also for some buttoned barrels, it's best not to be effin' with it after it's done. Small alterations like turing a 0.800" muzzle down for a 0.750" sight tennon might not be too bad, but taking the same blank down to a 1/2" suppressor thread can really fuck up the bore dimension right at the point where it matters (maybe) the most.
-Nate
