I uncovered 3-inch .410 shells/guns from 1933 described on a cartridge collector site, but I'm having trouble finding reference to when a 3-inch 12 gauge first came along. I have an old single barrel 12 gauge 3 inch that I suspect is from the 1930's or before.
1939
If it indicates that it will accept a 3 inch shell, it is a magnum. If it is marked 2 3/4 inches, it is not. Unmarked- not.
When were 3inch magnum
An Ithaca model 51 magnum 3 inch shotgun is worth $275-$325, depending on condition.
Yes, they are all high brass and considered magnum loads
The longest shotgun shell that you can safely use in your 12 gauge shotgun are 3 inchers.
Yes
Yes you can you can shoot 3 or 2 and a half in
Usually not, unless the shotgun is poorly maintained, too old, or poor quality to begin with.
100-400 USD depending on condition.
$139.95
i think the 50's at least