Actually there were no A-5's that were made in Missouri. Believe you are referring to an American Browning Auto 5. The barrels simply state "Browning Arms Co. St. Louis mo." This is what is called an American Browning. These guns were produced by Remington in the US (New York) for Browning after Belgium was overun by the Germans in WWII. The guns were made using Remingtons model 11 equipment. A few modifications were made to incorporate more of the Browning features and were all stamped Browning Arms Co. St. Louis Mo. All of these were made between 1940 - 49. Value is too difficult to be accurate without seeing the gun. Condition which includes the amount of original finish and original configuration will determine value. Auto 5's with poly-chokes, compensators and recoil pads will reduce value. A rough ball park figure would be $250-$600 range for this gun. Near mint guns and original box will command an extra premium. Recommend taking it to a gun shop for appraisal.
I would need to know what model of shotgun we are talking about before I can say when your browning was made.
Browning never made a Model 51 shotgun.
AFAIK they never made a bolt action shotgun
1962.A Browning light 12 shotgun with the prefix of 3G indicates that your shotgun was made in the year 1963.
100-1000 usd
Need serial number to date any Browning firearm.
1943 browning light 12 belguim made $5K
Are we talking about a auto-5 shotgun,or a BPS(browning pump shotgun),or a over-under shotgun(citori, or superposed)These answers would help me determine the value of your shotgun which was made in 1980.
Minimal
100-10000 or more depending on model
Requires professional evaluation.
Your browning auto-5 shotgun was made by FN of belguim for browning in 1938.In the condition that you describe your shotgun should be worth between 450-550 dollars.