Home Forums Hunting & Shooting Winchester Collectors pre-64 M70 barrel markings

I have an all original pre-64 M70 .300 Win. Mag. barrel that I had removed from an original action (SN 571xxx). However, it is marked 30-06 under the barrel where calibers were usually ID ed by the factory. Was this a common practice on .300 Win. Mag. barrels? thanks