This gun would have been made by Fabrique Nationale in Belgium. If its the old Auto 5, then it must be at least 40 years old but could be substantially older. I think ventilated ribs were added in the sixties.
Belgian made Brownings are prized outside of the USA as they are considered higher quality than US or Japanese made Brownings. If it is in good condition, buy it. Its not particularly valuable but would be a nice collectible and nice to have.
ENJOY SHOTGUNNING and try ISSF Skeet