300 win.
No, the 300 ultra mag cartidge is not interchangeable with the 300 win mag.
.300 WM is larger in calibre, it has a longer case, and it generates more energy.
Rifle chambered in one of the cartridges named Winchester Magnum- such as the .300 Winchester Magnum- or .300 Win mag for short.
Check the date code on the barrel, see related links for information on the Remington Society of America.
If you are asking what was the sn of the first post 64 Model 70 in 300 Win Mag, you will have to gain access to the Winchester records to find out.
Biggest physical difference is case size and lack of belt on the RUM
The M69 suffix identifies your 300 win mag as being a browning BAR that was made in 1969.
What is the Value of a Remington 770 300 win mag with a scope serial number M72031826
1976
1963
3500.00