I found an old spent shell one day on some state property a few years back, never got around to looking into what it may be from. there are no markings on it, and no primer in it. Its larger than a 12 gauge, i do not have a 10 gauge to compare it to though. ill get the specs of it and then post pictures. im thinking its from a flare gun, but there was no water around this property.
Brass
3" long
.926" outside diameter
.839" inside diameter
.250" primer opening
Brass
3" long
.926" outside diameter
.839" inside diameter
.250" primer opening