If you own an old single-shot, break-action 12 gauges then you know they aren’t very accurate and the recoil is enough to leave you sore black and bruised. There are ways improve this shotgun to make it better and actually make it more enjoyable to shoot with.
Forcing Cone and Lengthening
There is a section of the gun called the forcing cone. This area is in the barrel of the gun, just in front of the chamber. The forcing cone is slightly taper down to the rest of the bore and is normally less than an inch in length. Its job is to force the shot down to the size of the rest of the bore, this can be a very sharp angle.
There is a correlation between forcing cone length and recoil/accuracy. The forcing cone is meant to catch stray pellets and bring them back into the pattern. Lengthening the cone and changing the angle will also prevent the pellets at the back of the shot from being pushed down. With a gradual slope, the shot can condense at a slower rate, resulting in a tighter shot pattern.
If you don’t know physics, you probably heard, “every action has an equal and opposite reaction”. This is true in shooting, when a shot is triggered the compressed gas from the shot hit the step angle in the forcing cone and then goes right back into your shoulder. By smoothing this out, this makes it more of a steady compression, thus most of the gases leaves the front of the barrel. The remaining gas that are bounced back will be spread out over a longer distance, this lessens the recoil.
So if you have that old single action shotgun in the closet why not send it to a gunsmith to put some life into it.
Source: Wikipedia, Youtube