Buy a Mossberg or Remington. Either brands are readily available, rock solid and reasonably priced. A second barrel will only run 150 or less and can be changed in 30 seconds.
I have a Mossberg 9200 autoloader and 2 barrels. A 24 inch rifled slug barrel and an 18.5 smooth bore riot barrel. I added a side saddle(5 rounds on the stock) a flashlight and a laser. Works for hunting and any other need that may arise.
I have a 9200 I bought in 1998, never fired it. 18”, parkerized.
Like it?