The most likely answer to the barrel conundrum is that the Winchester barrel is a gunsmith pull-off which was kept until a previous owner needed a barrel for this rifle.

Pull-off barrels are common because actions are used for sporters in other calibers, i.e. 270 Winchester. Most gunsmiths have a largish pile of old barrels in varying degrees of servicability. Some are only good for hollow bar stock. Others are about "new".