Browning A5 Light 20 Bluing and Barrel Age Help!
 

Hello all,

I just bought a 1967 Belgian A5 20 in near perfect condition! I have some questions about the color of the blue and the year of manufacture of the barrel though. The receiver I know for sure is 67 as it starts with 7. The number on the barrel is M79783 and Ive been having a tough time finding any consistent information on how to date it for sure. From what I understand, the M means 20 but I'm not sure if the 7 behind it confirms it's a 67. Also, the blue on the barrel is quite intruiging to me. It's almost a reddish color, different from anything I've read about genuine blue colors. The barrel color is consistent and doesn't have any pits or dings. If someone reblued it, they had to have done a damn good job. So why would it be reddish? What concerns me is that the blue is different in color form the receiver. The receiver is darker with just a hint of gray which is period correct from what I've read. I've heard the blue can change color over time (is that even true?). I'm just looking for some guidance and confirmation. Please help!

Also, the barrel is for sure a Belgian as it was made in Belgium. Another point of concern is the vent rib on the barrel matches the color of the receiver, making this even more confusing for me to figure out

I believe it's called "plum" colored bluing. I think it has to do with the steel alloy used in the Belgium-made barrels and is unique to them.
Finland had contracted with Belgium to provide rifle barrels during WWII. They all came in that "plum" color. Plum colored, Belgian barreled, Finnish mosins are highly sought after.