Hi-Tech from 47 years ago. The first commercial mass produced in line muzzle-loaders.
This is the Huntsman 12 gauge. 40 yards is absolutely max. Rather have 20 to 30 yards.
I am rotating guns.
(https://hosting.photobucket.com/images/e328/reflex264/huntsman%2012.jpg?width=1920&height=1080&fit=bounds)