Trying to find Information about this gun. Springfield 5100

[Driver]

My father gave me this gun about a week ago. He has had it forever and he got it from his Grandpa.
From what I can tell its a Springfield 5100. The but of the gun is plastic. Im just trying to find out as much info as a can about it. Im not interested in selling it at all but it would be nice to know how much it may be worth. Here are some pics of the gun.

These two pictures are where it says "SPRINGFIELD J.STEVENS ARMS COMPANY Chicopee Falls, MASS. U.S.A." This is on the left had side of the gun just under the barrel.

This picture is where it says "Selected Forged Steel" "Proof Tested - 20 Guage 2 2/3 Inch Chamber" This on the top of the barrel.

This Picture is where it says "5100" This is on the right had side of the gun under the barrel.

This picture is of some kind of marking on the bottom of the gun by the triggers.

These are just some more pics of the gun.

 

[Hoosier8]

Springfield was a trade name used on Cresent Fire Arms Co double shotguns until about 1920 or 1921. This trade name was used by J. Stevens Arms Co. after 1920.

Stevens bought out Crescent and used the Springfield name until it was discontinued in 1948. The 5100 is the same as the 311.

The furniture is Tenite, an early plastic that becomes more brittle with age.

It still shows case colors but looks like some rust on the barrel? Not really a collectible so value is probably around $150, 100% = $275 in bluebook for a 311. It would seem to be worth more to you as an heirloom.

 

[g+16]

good looking for a old double barrel