One that has a reciever made by metal stamping rather than machining. The AK47 is one such gun.
The caliber of the firearm should be stamped on the barrel.
Mainly identified by features, not a stamped number.
often the model and maker are stamped on the weapon
If it's an NFA tax stamped device or firearm, yes. If it's a typical Title I firearm (your 'everyday' sort of gun), no.
Should be a .25 ACP. It should be stamped on the firearm.
Marginal value.
A small oval, containing the letters ELG, stamped into the metal of a firearm, would indicate the gun was made in Belgium, and was tested by the government Proof House in Liege Belgium.
THey were made by crescent firearm company.
Most firearms have the model number/name stamped on the receiver or barrel of the firearm in question.
A Sears and Roebuck firearm called the Gladiator Field Grade side by side manufactured by Meriden Firearms could sell at auction for up to $250. If there is a maker's mark or a model number stamped on the barrel, the price will be more than if there is nothing stamped.
No, unless it's an NFA tax stamped firearm (short barreled rifles, full auto weapons, etc.)
The manufacturer is normally stamped on the firearm next to the model, caliber, and serial number.