This shotgun was modified from a French military musket, probably an 1853 style that was manufactured at the Arsenal at Mutzig. Imp ale is an abbreviation for Imperial, indicating the weapon was produced some time after 1852. Durring the period immediately proceeding the Franco Prussian War 1870-71, the French took large numbers of obsolete muskets and turned them into breach loading firearms. These were subsequently sold off to Belgian arms dealers after the French defeat by the Prussians in 1871. The Belgians modified them once again by making them into shotguns for the civilian market. You have one of those shotguns.
100 yrs
this is not exactly an antique or anything, mossberg made tons of these inexpensive shotguns-retail value:$75-$90
The value of any "Antique" is always a very subjective opinion. research what a similar item has sold for and you will have your answer.
$500
If you have a semi-new shotgun, you can pickup the gun buyers guide from borders or a local book store. If your talking an antique shotgun, then they may have books for that, but I have not looked into it before.
Library, internet, Standard Catalog of Firearms.
See related link.
A Damascus twist steel double barrel shotgun is an antique shotgun made by layering iron and steel and welding them together. This kind of shotgun is worth approximately $3,000 depending on the condition of the weapon.
500 to 1500
Really not possible to answer without gun in hand. Value of antique arms is driven by condition.
The 20 ga shotgun was created by reaming-out the 50 cal. militery musket. I have only seen one.
Email us exactly how your shotgun is marked. gunshop@nctv.com