Depends on why the gun is illegal, If you are a person that has been convicted of a felony (a serious crime) then possession of a gun is punished by 5 years in a Federal prison. No probation, no parole, no concurrent sentence- and a fine of up to $10,000. Make that an unregistered sawed off shotgun, or an unregistered machine gun, 10 years in a Federal prison.
You could be severely fined and even spend time in jail. You would also be subject to investigation while the authorities find out if such gun was used on other crimes. They of course could "fabricate" a crime with your unregistered gun in such a way that you either pay a bribe or face a sentence for a crime you didn't commit.
In the US There is no Federal registration of firearms in the US. Most states also have no registration. Therefore, pretty much all guns are unregistered and may be kept in the home as any other property. Some places like New York, New Jersey, California and Washington, DC have more restrictive laws. Be sure to check them.
In MOST of the US, there is no requirement that a firearm be registered, with the exception of machineguns, sawed off shotguns, etc. IF your STATE requires registration, whether the gun is in working order or not does not matter. Without knowing where you are (and you did not tell us) we can't begin to guess. Sorry-
Why would a jury at Coroner's Inquest believe that the deceased would attempt to sell an unregistered gun to a county sheriff without success and later use that same gun to shoot himself?
In US, constructive possession of a gun is possession of all of the parts of a gun, even if they are not put together. For instance, it is not illegal to own machine gun parts. It is also not illegal to own semi-auto AR15 rifles. It is illegal to own full auto AR15 rifles that are not registered. Having a semi-auto AR15 and the parts necessary to convert it to full-auto would be the same…
While there are several gun manufacturer\'s that offer serial numbers on their shotguns, unfortunately the Mississippi Valley Arms Co. does not. The year and gauge of the gun would depend on when it was manufactured. For example, Mississippi Valley had numerous shotguns produced by a subsidiary company called Crescent Firearms, while many were imported from Belgium.