I have a factory savage stainless barrel that was given a custom chamber= 338 win factory re-chanbered to 338 edge........it shoots 1/4 moa easily.
My only other factory savage barrel is a 338 win and it shoots 0.4moa with the first and only load I worked up for it.
So................I really think other than tikka savage has one of the best factory tubes kicking around but like any real accurate gun: it needs set up that way, optics, mounts, bedding, stock and ammo. If you lock down all those issues, they are perfectly suitable for about anything this side of professional bench rest competition.
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After market is still "next level" IF it's done right.
I have aftermarket tubes that shoot 1/8 moa easily if everything is locked down.
All my aftermarket barrels (just a few+) are stainless except one and oddly enough it's the only one that does not significantly beat my factory tube, It's about the same group actually maybe slightly easier to clean. From such a small test group it could be a fluke but I lean toward stainless when ever possible.
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A friendly machinist I know once told me stainless was easier to machine. I always kinda figured it might lead to smoother machining processes as a result.
With Apache GW's $200ish barrels or hand lapped $300ish barrels available how ever I want them (contour,length,threaded,etc.) it's pretty hard to spend very much on any factory tube but for what they are there aint a dang thing wrong with factory.