To clean or degrease, nothing is faster than the aerosol cleaners.
You need solvents and lubricants to clean. Always buy a bigger bottle than you think you'll need, there is no point in being cheap with cleaning solvents.
A sign of hard use and heavy loads, the gap between the barrels and standing breech of this shotgun are an indication its time has passed.
A fired shotgun is different. The bore will have plastic in it from the shot cup. Some lead-pellet loads with cheap wads will have lead streaks where the shot flowed between the petals of the cup and contacted the bore. You had better hope your steel-shot shells don't feature cheap wads, because steel shot flowing between petals of the cup will score your bore. The plastic build-up will be heaviest at the forcing cone and choke, where the stresses on the wad are greatest. Your action may have powder residue and unburned powder in it, but action cleaning will be covered later with each type of shotgun.
Check to make sure the shotgun isn't loaded. Remove the barrel or barrels from the receiver. (Skip ahead to find your action type, or consult the owner's manual.) Clamp the barrel in your padded vise. With your cleaning rod, run a dry patch down the bore to wipe out the loose gunk. With a brush on your rod, brush the bore, and then swab with the dry patch again. Take a clean patch and place some cleaning solvent on it, and swab the patch through your bore several times. Clean the bore brush. Brush the bore and swab it with a dry patch. Repeal this process until the dry patches come out clean.
This is the traditional process, and it works. But it is a bit time-consuming. For some reason I have always been drawn to the high-volume shooting sports. While a skeet or trap shooter may go through 25 shells in 20 minutes shooting clay pigeons, a bowling pin shooter or practical shooting competitor could go through that many in five minutes. And then do it again 10 minutes later. My practice routine for bowling pin shooting takes 96 rounds and just under half an hour. With that kind of shooting, bores get packed with lead and plastic. No one wants to spend more time cleaning than shooting, so I worked out a few tricks to speed things up.
A plain old copper scrubby such as this one is perfect for cleaning your bore.
First, get a bore swab. The kind that looks like a fuzzy caterpillar on a stick. Go to the grocery store and buy a copper scouring pad for cleaning pots and pans. The pad should be one of the copper mesh type. Cut the pad apart so you have strips of copper mesh that are at least six inches long and as wide as your swab is long. Wrap a strip around your swab. To clean, forget the first dry patch and run a patch damp with cleaning solvent down the bore. Take your copper-wrapped swab and use it as a bore brush. You may have to compress the swab and wrap the mesh tightly in order to get it to fit into the bore. Stan the swab from the chamber end. Scrub back and forth, paying particular attention to the forcing cone and the bore a couple of inches in front of the forcing cone. Plastic builds up in the forcing cone as the wad first slams into the bore, exiting the shell. As for the ring in front of the forcing cone, I can only figure that it is the location in the bore where the heat, friction and pressure are at their maximum. Either that, or it is the location where some sort of rebound of the wad happens after its first compression by the forcing cone.
Pull the swab out and swab your bore with a dry patch. The patch will come out a disgusting black mess. That's a good sign. The swab will probably have strips of plastic and chunks of lead in it. Unwrap the mess. Clean the swab and mesh. Re-wrap the swab, wet-patch the bore again and then re-scrub with the mesh/swab. Two or three applications of this method and your bore will be clean. If you want to, you can do it to a bore you think is already clean, and see how much stuff you pull out. To clean the choke, take the cleaning rod without the last segment and handle on it. Install your swab/mesh cleaner and start the handle end of the rod through the chamber. Pull the rod through the bore until the scrubber reaches the choke. If you try to swab the scrubber back and forth it will expand as it passes out of the muzzle. You won't be able to force it back in. Instead, rotate the rod. If you have screw-in chokes, turn the rod in the direction that will tighten the choke. Once you have turned the scrubber three or four rotations, pull it out and run your dry patch through. Inspect the choke and if there is any more lead or plastic left, scrub again.
The copper mesh is softer than the steel of your barrel, so you can't harm the bore with it. As a bonus, it also works on rifled shotgun barrels, cleaning lead and plastic out of the grooves of the rifling.
For the chamber, choke up on the cleaning rod and hold it 6 or 8 inches from the swab. Insert from the chamber end, and press the swab against the sides of the chamber as you scrub back and forth. If you try to clean a chamber this way with a regular brush you'll destroy the brush in short order. The swab doesn't care, and you will quickly scrub the plastic and powder residue out of your chamber.
With the rod, brushes and patches handy, you can scrub a bore sparkling clean in a few minutes.
Single-Shots
The single-shot is an easy shotgun to maintain. While some will have exposed hammers and others internal ones, they will all have a lever or something to open the action. Single-shots open by pressing the lever and allowing the action to pivot open on its hinge. The single-shot exists for safety and economy. A single-shot shotgun that is broken open cannot fire. It can easily be unloaded. Those with an external hammer cannot be fired until after the hammer is cocked. With a single barrel to fit, the shotgun does not require the elaborate regulating that a double does. By slightly bending the barrel, the manufacturer (or gunsmith) can move the pattern center up or down, left or right. The low cost to manufacture a single makes it attractive to shooters and hunters wanting a starter gun for a new shooter or hunter.
Open the shotgun to make sure it isn't loaded. Close the action and remove the forearm. On some inexpensive singles, the forearm is held in place by a screw that attaches to the stud under the barrel. On others, the forearm has to be pried down from the barrel. Look for a single screw, If present, remove it. If there is no screw, or two, pry the forearm down with your fingertips. Expensive singles may have a small lever inlet into the forearm that unlatches it from the barrel.
Here is a typical example of a single-shot shotgun.
A single-shot shotgun has only one barrel, and usually hinges open to expose the chamber.
On singles and double, the forearm protects you from the mechanism and vice versa. The dismounting method is not always apparent.
With the forearm off, open the action and the barrel will hinge down far enough that you can lift it out of the receiver. Scrub the bore. A basic cleaning of the receiver does not require removal of the buttstock. Scrub the breechface, water table (the flat or curved area of the receiver where the chamber rests) and the hingepin. If you use a water-based cleaning solvent, use a heat gun or blow dryer to evaporate the water. One advantage to the single- and double-barreled shotgun is that the receiver is well-sealed against the elements. Unless you are out in the rain, or take a spill into the water, there will be no need to get inside the receiver. If you have, the easiest way to clean singles is to remove the receiver from the stock and dunk it in solvent. Most inexpensive singles (which is most singles) have their buttstock attached to the receiver