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

Does the exposed marking have an R in a circle for registered trademark or the more common "Winchester Trademark" marking? As far as I knew, all 300 Win Mags were marked with the circled R. I have seen a few 300 Win Mags not marked that way recently. I don't know if they are from the Winchester Rollmark stamps getting out on the open market or if they are legit. I will check but think that the 300 Win Mags were unmarked underneath and were the only ones unmarked.

there is no "R" on the barrel and of course the proof mark is on top vs. the side like most pre-64s. thank you.

That was one of the last rifles produced. Anything is possible. They could have possibly been trying to use up 30-06 barrels. I'm sure they had a surplus of those that were probably chambered, but could be opened up to 300wm and then roll stamped later???

Pics would be very helpful.

According to Rule the 300 Win Mag was one of the few post 1959 barrels to receive an underside marking. That marking was 300M, re-designated from the 300 H&H. Also 300 Win Mag had 6 grooves compared to 30-06 4 groove barrels. I am going to say there has been widespread counterfeiting as far as 300 Win Mags. There were all supposed to be rollmarked with the the circled R in place of the "Winchester Trademark" (Winchester over Trademark) marking.

Good stuff mike. I have an original 300wm barrel. I need to check it.

thanks all for your input. This rifle was correct in all aspects I'm aware of: "458" stamping on action recoil lug, 6 groove barrel, correct front sight ramp, correct stock which I have with narrow checkering and vented pad, rear sight, etc. Just the 06' stamping under barrel which I"m wondering about, although mr. bsa's theory makes sense. I have Whitaker's book but I cannot find any comments he makes on the "R" on the barrel stamping. I don't have Rule's book which is much more detailed, although I've enjoyed and learned much from Whitaker's book over the years.

I have searched and found two other 571xxx 300 Win Mags with the standard Trademark instead of the circled R. I see the circled R trademark on 575xxx and later guns. Rules book is good but not perfect. The 06 stamping is baffling with 6 grooves as they specify 4 grooves for the 30-06. You just can't walk into a gunshop and find a pre 64 model 70 in 300 Win Mag to compare. They are few and far between.