Muzzle Blasts Online
August/September 1998      Volume 3, Number 4
Past Issues Index
Shot Patterns and Smoothbores


Smoothbore load. See enlargement for caption.
One of the things that make a smoothbore so versatile as opposed to a rifle is its ability to use shot for clay targets and smaller game. However, few shooters ever take the time to get the most out of their guns. They will spend hours on the range to get the proper fit of patch and ball, then more hours getting the right powder charge. When it comes to shot they just dump a powder charge down the barrel and stick in a wad or two, then an equal volume of shot and an over-shot wad, and go hunting--often to somewhat less-than-hoped-for results.

The fact is that in order to shoot shot in a smoothbore you have to spend as much time (and quite possibly more) to work out the bugs. Like rifles, smoothbores are very finicky as to what they will shoot well. Rarely are two alike. One gun shoots #4 shot to a perfect pattern and the next gives a pattern that you could sail a dinner plate through without a scratch. I really can't tell you why, only that it happens. Here are some hints you might try if you'd like to improve your patterns.

First of all, most smoothbores bought off the shelf have not been subjected to the tender loving care a custom gunsmith would give his guns, so your barrel may still have some boring (machining) marks in it. A cleaning rod with "0000" steel wool run up and down in the barrel a couple hundred times will go a long way to make your bore smoother. (It also helps your accuracy when shooting the patched round-ball.) Once that's done it's time to go to the range.

Just about everything I've read on patterning a shotgun or smoothbore says to pattern the gun at thirty yards. Why? I feel that you should pattern your gun at the distance you intend to shoot. If you intend to shoot at twenty-five yards, set your target there. A smoothbore has no choke; it is cylinder bored, so its effective range will be limited. More on that later. First we need to develop a load.

I would suggest that you start with an equal volume load, which uses the same volume of shot as of powder. Repeat: volume, not weight! With my fusil, a .62 caliber (20 gauge) I would use the 7/8ths of an ounce of shot setting on my Lee shot measure for my powder measure. This throws 65 grains of FFg powder. I then add an overpowder hard wad which is .125" (1/8") thick. Then I put in two "Ox-Yoke Orignials" Wonder WadsTM cushion wads that I've lubed, and then the same measure of shot that I used for powder. Over that I use an over-shot wad that is only .030" thick. It helps to poke a hole in it with an awl or knife to ease loading. (That lets the air escape, but not the shot).

You've got to visit the range to find out what's required. If you intend to shoot at twenty-five.

This gives me a place to start. I will now shoot three or four of these to see how they pattern. I set up my 36" X 36" target at twenty-five yards, load as described, prime the pan, and shoot. Looking through the spotting scope I see that the bottom half of the target is well covered with shot, but the top half got away Scot-free. This tells me that my POA (point of aim) has to be adjusted. Aiming (or should I say pointing) a smoothbore is easy once you know where the shot is going. Don't get out your file yet; shoot two or three more to make sure they all go low. Then adjust as necessary. You now have your POA and should be able to aim at the center of your target from here on out.

Determining POA (Point of Aim) is the first step in finding out how youur smoothbore deals with shot. Here it is low and to the right.
If there are gaping holes in your pattern there are other things you can try. The first of these would be to cut back on the powder five grains. Rarely does increasing the powder help; in fact, it will normally worsen the problem. Try three or four shots that way. Then try a different wad arrangement. There are many different wads on the market, even the new plastic shot cups, though I don't think you will find them for most muskets, as they are made mostly for 20, 12, and 10 gauge modern shotguns. My Brown Bess is considered an 11 gauge, and I haven't been able to find wads for it.

When you make any changes, change only one thing at a time, like the powder charge. Then shoot three or four shots and write down the results. This will save valuable information and avoid duplication. I normally carry a small note pad and pen when I go to the range. My memory is less reliable than a written record.

Once you have worked out the best wad arrangement, you might want to see if shot size is a factor. As we stated earlier, some guns will shoot #4 shot well and others won't. You will have to try several different sizes to see how they pattern out of your gun. Of course what you plan to shoot at makes a difference too; you wouldn't want to use #4 shot to shoot sporting clays, just as you wouldn't use #9 shot to hunt turkey. Once you've got a good pattern, shoot it at 20 yards, then 30, 35, and even out to 40 yards. This will show you what the effective range of that load is, since the pattern will hold together only so far. Now go up to the heavier, or hunting loads (more powder/more shot) and do the process over again, but don't ever exceed the maximum load recommended by the gun's manufacturer.

Here is a good example of a bad pattern. A quail could have flown through some of those holes and felt only a breeze.
There are so many possible powder/shot combinations for each gauge gun that it would be an exercise in frustration to try to list them all. The Lyman Black Powder Handbook lists 1 1/8 ounce of shot as the heaviest shot load for a 20-gauge gun, which when used in equal volume gives an 82-grain (FFg) powder load. I see no reason to exceed that. They also list 102 grains of FFg and 1 1/2 ounce of shot for their largest 12-gauge load. Finding wads to fit your smoothbore may be difficult and you may have to buy (or better yet, fabricate) a punch and make your own. That's the way it was originally done. [Ed. note: Check the ads in Muzzle Blasts; Gary Butler of Circle Fly (812) 537-3564 is a source of all sizes of wads for smoothbores.] The standard load is: powder, an over-powder hard cardboard wad, a soft (usually 1/2" thick) cushion wad that had been lubricated, the shot charge, and then the much thinner over-shot wad. Most shooters end up with something other than "the standard load."

This laminated cardboard backing for the target opens up to show penetration through seven layers--obviously enough for small game.
Another thing we need to be concerned about is shot penetration. When hunting any game our load needs to not only get there, (which may require your getting closer to the game); it also has to cleanly harvest that game. Shot that hits a bird or an animal and wounds instead of cleanly harvesting is not acceptable. In order to know that your load will work, you've got to test it. What I've used is a laminated, corrugated cardboard test target. It consists of up to twelve layers of cardboard laminated together with white glue. Each layer has the grain (that is, the corrugated filler) going 90 degrees from the previous layer (just like plywood). If #6 shot will penetrate six to seven layers I feel it is good for small game like rabbits and ducks; #4 shot must penetrate at least ten layers for me to use it for turkey. There's nothing scientific about this test; it just makes me feel better about my load. To test the smaller shot for shooting clay targets, just tape some string to a few of them and hang them from a tree in a safe shooting area. Then get back to your normal distance and see if your load will reduce them to powder. These are simple but effective ways to test your loads.

It takes time to work up a good load for a rifle, and it takes time to work up a good load for shot, but when you see those clays turn to dust or walk toward that twenty-five pound gobbler you've been calling in for the last three hours, you will be paid back many times over!


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