1963
what goes father a 300 short mag or a 300 mag
No, the 300 ultra mag cartidge is not interchangeable with the 300 win mag.
300 win.
The term 300 mag usually refers to the .300 Holland and Holland magnum rifle cartridge.
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.
Ruger's web site has extensive sn data.
Check the date code on the barrel, see related links for information on the Remington Society of America.
300 mag is much bigger bullet
No known published sn data in the US
300-500m
Biggest physical difference is case size and lack of belt on the RUM
Check you barrel code on the Remington Society of America... http://remingtonsociety.com/rsa/questions/barrelcodes