Gunsmiths, gun collectors, gun-oriented internet forums, you might find someone at the gun show who'll know something about it.
To identify poetic patterns
Barrel marking, chamber cast.
Using colors to identify patterns in a poem
It was made for marking trees
It would be almost impossible to identify a gun just by its serial number.
You might find them in the Blue Book of Gun Values.
By maker information.
impaired visual acuity
Basically impossible to identify with just the serial number.
Books, gun shows, gun shops, pawn shops.
The compressed air gun, which shot metal bb's was invented before the paint marking gun.
CBRN standard marking kit