Blue Book of Gun Values
50 USD
10-40 USD or so
I do not personally, but yes, there is a single shot rifle that can have the rifle barrel replaced with a shotgun barrel.
the value of this rifle was100$ American
Impossible to answer without a detailed description of all markings and condition.
10-100 usd
Yes it is. It is a single shot .177 pellet rifle. It is not a BB rifle.
Generally, no. While single shot rifles MAY have the rifle barrel replaced with a shotgun barrel, reverse is not true (usually) A rifle cartridge generates much higher pressures than a shotgun shell.
Seldom exceed 100 USD
10-100 USD; @ turn of the century give or take a few decades.
As you probably know, a Cape Gun was usually a side by side, one barrel being a shotgun, one being a rifle. Shotguns were usually 16 g is Europe, and 12 g for sales in the US. I know of no complete listing of the rifle calibers- .38-55 and .32-40 examples are common in the US. European guns usually use a European cartridge, such as the 9.3x72R. PS-amended the spelling of Pieper- search for Henri Pieper of Belgium, you will get more results.
50-100 USD