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.
If you're lucky about £400.00
The value of a Henry van Wart muzzle-loading shotgun from the Civil War era can vary significantly based on its condition, historical significance, and provenance. Generally, such firearms can range from a few hundred to several thousand dollars. For a more accurate appraisal, it’s best to consult a firearms expert or auction house specializing in antique weapons. Collectors often consider factors like rarity and original features when determining value.
$500
Library, internet, Standard Catalog of Firearms.
50-500 USD depending on specifics
TOO COSTLY, RUINS THE VALUE, CHEAPER TO BUY A NEW ONE ABOUT $150
500 to 1500
Really not possible to answer without gun in hand. Value of antique arms is driven by condition.
Around US$ 2,000 depending on its conservation status. Without DETAILED descriptions the range could be 100-10000 USD or more. While they may be old, a 1900 rifle is NOT legally an antique. US law has a specific legal definition of antique firearm, Unless they are muzzle loading guns, they must have been made in 1898 or earlier to be an antique. Values will be based on specific make, model, condition, and originality. without detailed information, we cannot even make an educated guess at value.
Value will be determined by how well it looks over a fireplace. Normally from $100 to $250.
Isaac Hollis & Sons were noted British gunmakers from c.1860-1900. They made many top quality shotguns and rifles with many levels of ornamentation. This is one that should be individually hands-on appraised. sales@countrygunsmith.net
Seldom beyond 100 USD or so