Take it to a gunsmith
The users of them.
How much is a 16 gage single barrel shotgun model 350A Revelation
I do not personally, but yes, there is a single shot rifle that can have the rifle barrel replaced with a shotgun barrel.
about $100 US.
yes they made a martini action single barrel shotgun 12gauge it is cheap around £100 but it has a huge amount of recoil you can buy them on guntrader.com
The Model 1894 Remington was a side-by-side shotgun. The Model 1893 was a single-barrel shotgun with a side hammer. The 1893 in excellent original condition can bring $300.
An early model Lefever single-barrel 12-gauge shotgun with a 30-inch plain barrel can be found for sale online for $300. This is the price for one that is in excellent condition.