They built their rifles with a very specific purpose, to shoot high BC bullets out of a long barrel with a very fast twist. For them the marginal gain in FPS was worth the extra work and expense. And they like the fact they can neck down Lapua brass. Personally, I would not due it, especially in a rifle with a sporter barrel. Like others said, maybe 100 fps or so gain in standard length barrel. But if you happen to be a machinist and like the idea, go for it.
