You will need to call Browning.
What is the age and value of my Winchester model 70 264 win. mag super grade? Serial # 703942
The M69 suffix identifies your 300 win mag as being a browning BAR that was made in 1969.
By the serial number.
1946 to 2006
Impossible to answer without a detailed description of all markings, finish, barrel length, action type, condition, accessories, box, papers, etc..
I'm not sure when you posted this question, but I purchased a Winchester 264 win mag a few months ago at a gun auction. I bought it for $350.
How value is Browning 300 Win Mag Semi Automatic
100-1000 usd
Need a detailed description
You must call Browning with the serial number.
-80-800 usd