Seeing Shotgun Patterns

It is fun teaching the Shotgun Shooting Merit Badge to Boy Scouts. It’s also fun to see them transition from shooting rifles at fixed distances to trying to hit an orange and black disk moving away from them at the mercy of the prevailing winds. However, it is not fun watching them miss clay after clay. That is when my double standard rears its ugly head. When I miss shot after shot, I try to figure out what I am doing wrong.

That is my attitude with most adults—do not blame the equipment; check your form and preparation for each shot. That is one standard. However, when Scouts are involved, I start wondering what might be wrong with the equipment. That is an entirely different standard. As their instructor, I am responsible for two aspects of shotgun shooting: getting them into the form that will break clays, and making sure the equipment will not frustrate their efforts.

Maintenance Cycles A heavy maintenance cycle is not enough to ensure this. Equipment preparation is a routine task that needs to be provided weekly during summer camp. In my case this summer, I had a number of different shotguns; six Benelli M2, five Remington 870, a Remington semi-auto, a Stoeger double barrel coach gun, and an Ithaca pump, all in 20 gauge.

During the weekly maintenance cycle, I pull every shotgun screw-in choke, remove the barrel, and load as many metal pieces in the ultrasonic Students must learn to focus on the target, not the sights. Patterns tell the student how to align the barrel and anticipate their leading the clays. cleaner as can fit. After a short time, I take the parts out, inspect them, blow them dry, and put them in a heated oil bath to make sure all water is displaced.

As a quick aside, an ultrasonic cleaner can be a real time saver when cleaning parts for so many shotguns, such as an entire basket of chokes at once. While parts are in the bath, I scrub out the barrel and make sure the receiver and magazine tube are clean. After the bath, I wipe excess oil off the parts and reassemble the shotguns, carefully lubricating parts where they should be. After a function fire, I give it a final once over and place it in the armory for the next class.

For many gunsmiths and shotgun instructors, the task stops there. Another job well done—or is it? When you work on a rifle, the final test is to see if it will group. Some people want minute of angle, We seek a good variety so Scouts can learn what they like. All need a weekly cleaning as we averaged 1200 rounds a week. You can not give good instruction unless you know how the shotgun performs. Patterning is the secret to that knowledge. others are happy with minute of pie plate.

When is the last time you fired a shotgun to see if it would group? Wait a minute, shotguns fire shot so grouping is not an issue, is it? The answer is yes, but the language is pattern. If you are not familiar with the term, do not feel bad; the last time I sat in an NRA Shotgun Instructor Course, patterning a shotgun was not even mentioned and it has also been deleted from the BSA Shotgun Merit Badge book.

During the last two years, when I mentioned patterning to a shotgunner, most do not know what I am talking about, and the few that do are not aware of what pattern specifications mean.

Patterning the shotgun showed how dirty chokes impacted performance. Far A shotgun equipped with multiple choke tubes provides exceptional versatility to its owner at a lower cost than the custom fixedchoke barrels. On the other hand, not all choke tubes pattern as specified. Many are sensitive to the shells being used. Each tube should be patterned to determine performance.

In the majority of cases, patterns are something governed by the choke of the barrel which is either stamped on the barrel or printed on the interchangeable choke tubes that come with the shotgun. Simplifying the concept, patterning the idea that full choke is a tight pattern, modified is slightly more open, and cylinder bore is no choke at all. The Case for Patterning Let’s cover a little history. Early shotguns would be classified as cylinder bore.

Fred Kimble is credited with developing the concept of choking a barrel and boring it to achieve the desired pattern. Choke boring of barrels became common in the 1870s. Generally, barrels were bored and reamed as full-choke barrels until purchased by a customer who would specify the degree of choke wanted. According to Peter Harris in his article "The History of Shotgun Chokes", we find the first mention of chokes in 1827. However, it was W.

W, Greener who may have developed the first tools to correctly profile and bore barrels to full, modified, improved, and cylinder chokes. This occurred sometime around 1874. An alternative to reaming the barrel for choke, was to form the barrel with the choke on the outside near the end of the barrel. Machines swaged or pounded the barrel to a uniform profile on the outside. This forced the choke to be on the inside.

In either case, to meet the customer specification, a gunsmith would pattern the shotgun and determine the actual performance. If the shotgun did not meet the specification, the gunsmith would remove metal and try again. The process would be repeated until the shotgun and barrel combination met the customer’s specification.

Things started to change when experimenters (as most avid shooters are) discovered that placing a constriction in the last inch or so of a cylinder bored barrel was almost as good as a properly choke-bored barrel. Not only that, it was cheaper to produce and with a little ingenuity you could extend the usefulness of any one shotgun by making the constrictions interchangeable. Some interesting systems have evolved, such as screw-on external chokes designed to fit on the end of a threaded barrel.

You can still find Mossberg shotguns today that use the external chokes. Another system was the variable choke system offered by several manufacturers, including my favorite, Polychoke. The winning system, however, is the screw-in choke system perfected by Winchester as the Winchoke in 1970. This system became the parent of most of the choke tube systems in use today.

By back boring a cylinder choke barrel and then threading it, thin choke tubes can be interchanged that allow the shooter to use the choke best suited to the purpose. Full and extra full are often used for turkey or highflying birds, while modified and improved serve well for most game hunting and close-in birds. Modified and improved also work well for Skeet shooting, unless you have the specially designed skeet tubes. Cylinder bore is often used in slug guns or home defense shotguns.

I have seen as many as seven different levels of choke, but for now I will only talk about the most common. Note, these are the approximate values as listed in Jack O’Connor’s reference The Shotgun Book. Full choke is 70% of shot payload will be centered in a 30-inch circle at 40 yards. Modified, 60% of shot payload will be centered in a 30-inch circle at 40 yards.

Improved Cylinder is 50% of shot payload will be centered in a 30-inch circle at 40 yards, and Cylinder is 40% of shot payload will be centered in a 30-inch circle at 40 yards. With the mass production of shotguns prevalent today, an occa-

Far Close examination shows gaps where clays could escape even a well-aimed shot. This shows a Scout pattering one of the class shotguns on our homemade patterning frame. sional shotgun is function fired, but none are patterned. In the 1970s the wisdom was, if you were a serious shooter, you bought a shotgun, took it and a box of your favorite loads out to pattern in. Fancy systems used a patterning board, others hung up large sheets of paper with across drawn in the center and counted holes.

The thorough shotgunner would pace off 20-, 30-, and 40-yards and shoot at the board or paper, spraying it white or replacing the paper between shots. The board showed where the hits were and how dense the pattern was. You would draw a 30 inch circle around the center and count how many pellets were within the circle and examine where the densest patterns are. You would then know if your shotgun shot high or low, left or right.

You also knew if the load and shotgun combination were actually delivering the pattern promised by the fixed-choke barrel or the interchangeable pattern you used. Patterning Uses Since I am an NRA Shotgun Instructor and teach the shotgun merit badge in Scouting, I have found another use for the patterning board. The shotgun merit badge mentions choke, but no longer requires a Scout to pattern his or her shotgun.

I think that is a shame, because I have seen shotgun scores double after having a Scout pattern the shotgun they are shooting. It helps the Scout see what will happen as they are sighting on the clay and planning their shot. By the same token, taking time to pattern the shotguns I use for the class gives me great insight into shotgun and shell performance. Sometimes, swapping out shotguns will enable a shooter to score with one when they miss with another. On to constructing and using a patterning board.

The shotgun range where I was teaching this summer did not have a patterning board. It was not hard to construct one, and before long I had students standing 35 yards back from a 4’x4’ frame suspended about three feet above the ground and covered in brown paper with a target dot drawn in the center. Granted, this is not the correct distance to officially pattern a shotgun, but it was the practical distance to the clays on this range.

We either stapled or used push pins to fasten the paper top and bottom to the rectangular wooden target outline. I had them aim at the center of the brown paper and fire one shot. After making sure the shotgun was safely unloaded and properly racked, we walked down range to look at the paper. The paper did not look like much until they walked around and looked at the back side. There, the pellets’ perforations showed more clearly. It also showed something very interesting.

In one instance the pattern had six-inch nulls in various locations within the circle; more than large enough to miss clays. Another had a similar null dead center in the pattern. I had each class pattern two shotguns, one pump and one semi-auto, and compare the results. Each week I would collect additional patterns and encourage the Scouts to compare. Have you thought much about how design, function, repair extends beyond the barrel? In the case of shotguns, it certainly does.

In the early days of shotguns and barrel chokes, getting a shotgun to pattern correctly was an arduous task for the gunmaker and gunsmith. While expensive, the customer tended to get exactly what they ordered. Today with interchangeable barrels, interchangeable chokes, and endless combinations facilitated by CNC machining, the average shotgunner takes the pattern of his shotgun for granted. So does the manufacturer who rarely goes to the expense of validating the claims printed on their shotguns and chokes.

Sadly, patterning a shotgun is still an art, and a vanishing one. It is easy to set up to pattern a shotgun. Different manufacturers of guns and shells have different standards of what a "good" pattern is. As gunsmiths, if we don’t know how the customer’s firearm is patterning, we

Construction material was scrap 2×4 lumber glued and screwed together. The extended feet were drilled front and back for pegs driven into the ground to resist wind. Apiece of rebar served as the paper roll axle but apiece of PVC pipe or electrical mechanical tubing could do as well. cannot actually guarantee function beyond loud bangs. The simple patterning board or frame is an inexpensive diagnostic tool. When a customer brings a shotgun to your bench, ask what he or she intends to shoot.

If possible, request a few shells from their stock to correctly test the shotgun. Find out the distances they intend to encounter and pattern at that distance. You should not need to go past 40-45 yards as that is the standard for determining the effectiveness of choke patterns. Analyzing Results After test firing a shotgun, the rest is basic math and patience. For example, according to one chart, #8 shot provides about 410 pellets to the ounce.

A 20 gauge Federal Top Shot shell throws 7/8ths of an ounce of #8 pellets; that is roughly 358 pellets going down range. Using a modified choke tube, you should be able to count 215 pellet strikes inside a 30-inch circle at 40 yards. Even if you do not divide the circle into quarters and count each quarter, you should still be able to see where the majority of hits occur and if the barrel is shooting true. More often than not, you will find that the barrel throws slightly off.

With just this little bit of research you have something to show the customer. They may want to spend some money getting the shotgun to pattern to their specifications by trying different chokes where possible, or doing some barrel work on a fixed choke barrel. In the case of the shotgun with the dead center null, it turned out the wad was staying with the shot column and opening the pattern. By scuffing the interior surface of the choke tube, This was the reason the Benelli shotguns initially had poor patterns.

Patterning a shotgun before and after cleaning convinced students that a thorough cleaning was essential to maintaining accuracy. we were able to slow down the wad and restore the pattern. As an instructor this summer, I had a situation where more scouts were qualifying with the old 870 pump shotguns than with the expensive semi-automatic Benelli M2. We started patterning both and found that the Benelli shotguns were throwing terrible patterns. The problem turned out to be excessive choke fouling.

I ran a brass brush through to scuff up the deposits to make them more visible. Very careful attention to cleaning the Benelli chokes improved their performance on the Skeet range. As aside note, observing the cleaning issues of the Benellis led many Scouts to believe they would choose a different maker when purchasing their first firearm. The same observations provide me more information to share with prospective customers.

Once you learn to read a pattern, there are countless ways a gunsmith can help a customer shoot better and have more fun. On the other hand, if the customer paid money to have a specific pattern and that is not what they are getting, they may want to talk to the manufacturer. At least you have given them the facts to support their case. If you want to learn more about chokes and patterning, look up a copy of Jack O’Connor’s The Shotgun Book published by Alfred A Knopf, Publishers.

He devotes chapters to barrel forming, chokes, and patterning. This is a great resource for any shotgun shooter or gunsmith. You can find used copies of the book on Amazon and elsewhere. AG