Falling into a pattern

The red outline is a 30-inch diameter circle that is the desired pattern shape and size. The black outline traces the perimeter of the actual pattern.

Patterning sheet. The red outline is a 30-inch diameter circle that is the desired pattern shape and size. The black outline traces the perimeter of the actual pattern.

Call me eccentric, call me crazy, but I see no sense in measuring patterns at 40 yards because I seldom shoot at game birds at that distance. I want to know the pattern data at 25 yards – the distance at which most birds are shot.

Falling into a pattern

Mostly, it’s counting holes punched through a sheet of paper. Really tiny holes in a really big sheet of paper.

Patterning a shotgun is not the most exciting way to spend an afternoon, but on a sunny and windless day in January (even if the temperature is 5 degrees) it gets you out of the house and provides a temporary cure for cabin fever. An hour-long patterning session with your favorite bird gun may also provide information that will make you a better wing shot.

Or it may destroy your confidence in your gun’s ability to ever hit another bird on the wing. Life is full of risks.

Every shotgun has its eccentricities. So does every shotgunner. Pattern testing your shotgun can reveal a number of things about a gun’s ballistic performance (how it shoots from the bench) and about your performance with the gun (how it shoots for you).

Properly done, patterns tests bring to light at least six tendencies of your gun. In order of importance (my subjective rating of importance) those are:

  1. pattern size at various distances
  2. pattern density
  3. pattern consistency
  4. barrel registration (point of impact) from the bench
  5. barrel registration when you shoot the gun
  6. pattern differences with various shotshell loads

I use the word “tendencies” advisedly because I have learned there are no absolutes in a shotgun’s performance.

As every shotgunner knows, once the charge of shot departs the barrel and leaves the shot cup behind it becomes a cloud of pellets that grows increasingly large (longer and wider) as it travels farther and farther from the muzzle. A bird in flight can be brought down when it is struck by one or more of the pellets in that cloud. The number of pellet strikes required depends on the species of bird, the distance from which it is shot, the size of the pellet that strikes it, and the part of the body that is struck.

Given all those variables, the bird hunter wants his gun to shoot a shot cloud – a pattern of shot –that will most likely result in a sufficient number of pellets strikes on the game bird: a pattern with, on average, one pellet for each 4-5 square inches of area. This definition of correct pattern density is my conclusion derived from observing the performance of tested loads on wild birds shot afield; other bird hunters may say that pattern density must be greater or can be less.

Any discussion of pattern density has to include harsh facts about a phenomenon known as “shot stringing,” but we will open that can of worms later.

We control the size and shape of that cloud of shot fired from our gun by various devices, the most significant of which is choke. Choke is the constriction in the last inch or inches of the barrel that determines how the shot pattern will develop as it travels down range.

Shot pellets fired from a shotgun barrel with no choke (cylinder choke) spread out very quickly, and pattern density falls below that 4-5 square-inch-per-pellet benchmark at distances as short as 15 yards from the muzzle. Sometime in the 300 year history of shotgun development someone discovered that a few thousands of an inch of constriction at barrel’s end “tightened” the pattern so that it was still effective at longer distances, all the way out to 45 or 50 yards in some instances.

The concept of choke has been around a long time, but it has become an obsession in this era of shotgunning when changeable choke tubes offer the opportunity for the “perfect” degree of choke for every imaginable wing shooting situation. One shotgun information website lists nine types of chokes: .000 inch constriction – open choke, .005 inch – skeet; 010 – improved cylinder, .015 light modified, .020 modified, .025 – improved modified, .030 – light full, .035 – full, and .040 extra-full.

Nice as it sounds to have the choke tube that will help your shotgun deliver an efficient pattern at any distance you select, do not put much faith in these choke designations. Pattern test your gun and you will almost certainly discover that your pet load of 1 1/8 ounce of number five shot fired through an improved cylinder choke tube does not produce improved cylinder patterns at 30 yards every time. This may be a bitter revelation or a joyful epiphany, depending on your point of view.

So let’s start with the simplest of the patterning tests, the one that will demonstrate pattern size, density, and consistency. The “standard” way to conduct this test is to hang a 48-inch square sheet of paper on a frame, back off exactly 40 yards, shoot one shot at the center of the paper, take it down, estimate the center of the pattern, and draw a 30-inch diameter circle around that center point.

Count the number of holes within that circle, and divide that number by the total number of pellets in the load. For example, you shoot a 1-ounce load of number six shot (which contains about 230 pellets) at the patterning sheet, scribe the 30-inch circle around the thickest part of the pattern, and you count 138 holes within the circle. Divide 138 by 230 and you find that about 60 percent of the shot hit within the designated part of the pattern. You check the handy choke percentage chart and learn that you have a modified choke.

Which tells you next to nothing.

Another part of the chart states that a modified choke is the best all-around choke for wing shooting, delivering lethal patterns out to 40 yards. That information is of some value, but not much.

I test my shotguns’ patterns at 25 yards. Call me eccentric, call me crazy, but I see no sense in measuring patterns at 40 yards because I seldom shoot at game birds at that distance. I want to know the pattern data at 25 yards – the distance at which most birds are shot. In preparation for woodcock and ruffed grouse hunting, I like to know the pattern at 15 and 20 yards, too. For pheasants, it’s good to know how a certain gun and load pattern at 30 yards.

Conveniently, my pattern tests can be fired from the shooting table on my 25-yard rifle range, hanging the 48×48 sheet of paper on the same target frame I use for shooting .22 caliber rifles. I can also shoot from 15, 20, and 30 yards, but the shots are fired off-hand rather than from the bench, so they are less precise.

I do agree with the premise of the 30-inch pattern. Catching a bird on the wing within a 30-inch pattern of shot is a reasonable yardstick of accuracy, something that almost all bird hunters should be able to do. Conversely, most bird hunters reduce their chances of hitting the bird as the pattern size shrinks to 25, 20 or 15 inches diameter.

Today’s test

I hung the pattern sheet, with a 5-inch black dot in the center as aiming point, set my Lefever 16 gauge double gun on sandbags on the shooting bench, sighted down the rib, placed the front bead on the bottom edge of the dot, and pulled the trigger. Even though I was testing a relatively light load (Fiocchi hull, Winchester 209 primer, 19 grains Hodgdon Universal powder, BPI SG16 shot cup, 1 ounce of No. 6 Lawrence brand shot, 1,195 fps muzzle velocity) the recoil of a light gun fired from the bench got my attention.

I pulled the pattern sheet from the frame, took it in the clubhouse, laid it on the floor, found my 15-inch compass and a couple felt tip markers, warmed my hands, and got to work. I drew a rough outline of the pattern, ignoring pellets that were flyers, and counted the pellet holes within that outline: 182. I also counted the pellet holes on the pattern sheet outside the perimeter of the pattern: 27. Lastly, I estimated the center of the pattern strike, and used the compass to draw a 30-inch circle that represented the desired pattern.

Some disclosures

Pattern sheets: I recommend shooting patterns on at least three sheets when testing a load/choke. The compiled results of multiple test sheets will be more accurate.

Pellet count: 1 ounce of No. 6 shot should contain about 230 pellets. About 210 struck the pattern sheet, so what became of the rest? The charge bar in my MEC loader is marked 1 ounce, but it actually throws a charge of 15/16 ounce of No. 6 shot. Since I prefer light loads, and since these 15/16 ounce loads perform nicely, I have not bored out the charge bar.

As the accompanying photo shows, the load patterned well. The barrel shoots to point of aim, pattern size is optimum for a target at 25-30 yards distance, the pattern shape is excellent, and density is appropriate to the pattern size.

The red ovals marked in the upper right and lower right quadrants of the pattern indicate potential areas of insufficient pellet density. This is not particularly worrisome; other pattern sheets with this load/gun have exhibited more even distribution of shot. That’s one reason why I recommend multiple patterning shots.

Notes and conclusions

Manufactured in 1928, this Lefever shotgun has fixed chokes. When I acquired it, the pattern sizes were full choke from the right barrel and extra-full choke from the left.

Following my instructions, a gunsmith opened the right choke constriction to .007 inch and the left barrel to .015 inch. My intent was that the barrels would then pattern skeet and light modified. In fact, they pattern light modified and improved modified. Go figure.

The chokes/patterns of this gun with the 1 ounce No. 6 load perform well on prairie grouse and pheasants, so I have no reason to open them more. This gun/load is not suitable for my woodcock and ruffed grouse hunts, however. Shots in the aspen forests are invariably close, and birds hit are ruined as table fare.

Enough “choking” for today. My next essay will address some other aspects of shotgun pattern tests, including how to determine where the pattern strikes when you quickly mount the gun to shoulder and shoot.

I will also ruminate on the shortcomings of pattern testing: the fact that pattern tests are two dimensional and do not show the problems of long shot strings, and the nuisance that a pattern test shows only how your gun performs with the specific load tested. If I had tested a 1 1/8 ounce load of No. 5 shot fired from my 16 gauge, for example, it may have produced horrendously uneven and inconsistent patterns.

I hope not, because that is the load I intend to test in a couple weeks. If the weather warms up.


More stories about upland bird hunting are published in my collection of essays, Crazy Old Coot, and my novel, Hunting Birds. Both are available in Kindle and paperback editions at Amazon.com.


About Jerry Johnson

Curmudgeon. Bird hunter and dog trainer. Retired journalist and college public relations director. Former teacher, coach, mentor. Novelist and short story writer. Husband, father, grandfather.
This entry was posted in Shooting, Shooting Sports, Shotguns, Shotshell Reloading and tagged , , . Bookmark the permalink.

2 Responses to Falling into a pattern

  1. uplandish says:

    Good info there, patterning is highly overlooked in my opinion, even fewer know the proper way to do it. Hunters make sure their deer rifles are sighted but are loathe to waste few shell and some time to see how their shotgun performs.
    I look forward to reading your thoughts on shot string. I did a paper on shot string back in school, it was mainly an excuse to strap a piece of ply wood on the side of my Crown vic station wagon and take turns shooting at it with different loads while a whomever drew short straw drove it at various speeds.

  2. Great info about shotgun pattern you have shared with us. Patterning is highly overlooked. I am looking forward to know your thoughts on shot string.

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