I recently got around to unloading the duck boat we stored in the garage, stuffing the magnum mallards back into their decoy bags, and hoisting the Canada floaters aloft for summer storage. A task which should have been completed after the last hunt in the fall, but procrastination rules the day at the lodge. The deeks were right where we left them, scattered around the boat’s bottom and deck after the hunt last October.

As I completed the task of winding the anchors and storing the blocks, I couldn’t help but reflect on Dick’s miraculous shot on that Giant Canada (see Full Choke, May 2015 issue). The image of that huge bird dropping dead at the outer reaches of our decoys made me wonder if I would have been able to make a clean kill with a Full choke gun at that distance. Dick was using his Winchester Model 12, and the pattern it produced with HEVI-Shot must have been tight and dense. How accurately must a hunter execute a shot on game birds at distances exceeding 40 yards to place his payload on target? Dick was wearing multiple layers of heavy clothing, starting with a low gun, then skillfully executing a gun mount in a dynamic situation while adrenalin had his heart pumping wildly. Then he had to pull the trigger at the precise moment when the real and apparent leads were perfect, in parallel with a flawless follow-through.

The less informed frequently call them scatterguns and use the phrase “scattergun approach” when referring to people who don't have a plan. But I wondered to myself whether “scattergun” downplayed the significant skill required to humanely harvest game birds at long-range. Makes it sound like we just spray a huge cloud of shot in the general area of the target, confident that everything in its path will fall. Maybe in the days of the market hunter and the punt gun, but how much “precision” is required to execute long shots like the one Dick made on his goose, or like Dakota pheasant hunters routinely make on wind-swept birds during cornfield drives? I pondered the question, but didn’t quite know how to structure the analysis.

Margin for Error Table
For those who are interested in gaining some insight into the precision required to ensure a broken clay or a downed bird, this table identifies the margin for allowable barrel pointing error permissible during the execution of the shot. The table makes evident that the distance to the target, the barrel length of the gun (and associated sighting plane), and the degree of pattern efficiency deemed acceptable (defined as a 20” or 30” kill zone) all influence the amount of pointing error permissible in a well-executed shot. The Margin for Error Table presented here was developed employing an on-line, right angle Trig calculator (http://www.pagetutor.com/trigcalc/trig.html). We calculated the acute angle for various distances and pattern sizes and included maximum allowable error (13”) for those who are willing to accept the lower probability of success using the entire 30” pattern. By calculating the acute angle established by four different distances and two different pattern sizes, we were able to present the data in a more reader-friendly format.

But then the phone rang and it was Shotgun Sports editor Johnny Cantu. “Ron, I have a topic which I would like you to explore for an upcoming fall article,” he said. “I think it is a subject you could wrap your arms around. I’ve been thinking about an article titled ‘Margin For Error’ for about four years, and have decided that it might fit in nicely with other articles you’ve written employing analytics. Specifically, it occurred to me that many of our readers would be interested in knowing how precise they have to be in executing a shot in order to break a Station 4 skeet target with absolute certainty as it passes over the center stake. We know that only the 20” core of the skeet pattern contains sufficient pellet density to break a target each and every time, so what is the allowable ‘margin for error’ a skeet shooter must stay within in order to break that target every time? Give it some thought, and see if you can define the limits of precision required to break that target without fail.” I suspected Johnny already knew the answer, but saw benefit in getting another perspective on his theory.

In order to answer that question in its simplest terms, I decided I first had to deal with some of the more obvious variables which seemingly clutter the analysis. Did it matter whether the shooter was using swing-through, maintained-lead, or pull-away technique? Was it important to take into consideration the fact that the flight angle of the target in relation to the path of the shot was constantly changing? Would shot velocity, shot stringing or target speed affect the equation? You are free to disagree, but I concluded that I would have to ignore the variables related to gun technique and ballistics if I had any chance of isolating meaningful data. What I really wanted to know was: all of the above variables being constant, what are the limits of allowable barrel-pointing error which permit the world’s best skeeters to keep the target within the 20” core of the pattern?

  There are more variables in shooting skeet or wild game than most of us can recite, but this analysis, very arbitrarily, ignores the variables inherent in the execution of the shot and in the ballistics properties of ammunition and the shot string. Poor gun mount, incorrect swing and follow-through technique, and holes in the pattern due to shot balling, patchiness and shot stringing are all factors which will cause a shooter to miss.

But in order to determine how far a shooter is permitted to miss a target (margin for error), and still break the target 100% of the time, we have to assume that all other relevant factors are without flaw. The object is to determine how imprecise the shotgunner can be in executing his shot, all other relevant factors being favorable, and still be guaranteed that the target will break. In order to define the error limits, it was necessary to determine how far away the target could be from the intended point of impact and still break with certainty. Since there are no absolute certainties in life (besides death and taxes), we chose to define our limit as the perimeter of the standard 20” pattern core. At skeet distances (assuming a skeet choke, optimum shot size and volume), the 20” pattern core has proven over decades to be the area of the shotgun pattern that will effectively break targets nearly 100% of the time.

We also assumed that the target, which presents as an inverted 4” oval or elliptical saucer, must be positioned in its entirety within the 20” pattern core to assure breakage. This establishes the margin for error at the target as the distance from the center of the 20” pattern core to the center of any target location at the perimeter of the pattern, a distance of 8”.

But the burning question is: how is this 8” margin for error at the target perceived from the skeet shooter's perspective?

Our Skeet Example
We know that the target will be precisely 21 yards from the shooter on Station 4 (and on all stations) when it passes through the center crossing point. We also know, from articles on pattern placement analysis, that the distance from the shooter’s eye to the front bead of the shotgun is, for the average shooter, about 36”. So what we want to know is: what are the outer limits of barrel pointing error (Margin for Error) as visualized by the shooter, such that the target will always be inscribed within the 20” pattern if it is intercepted at 21 yards? To answer that question, I initially used the following equation: (distance from the eye to the front bead) divided by (distance from the eye to the target), multiplied by the 8” extremes of target location permissible within the 20” pattern. The answer would represent the amount of barrel movement error at the muzzle (bead) which is proportional to the maximum allowable target distance away from the center of the pattern (8”). Stated another way: it would tell us how much off center the muzzle (bead) could stray during the execution of the shot, and still intercept the target with the extreme front or rear of the 20” pattern.

We stated previously that we’re going to use 36” or one yard as the distance from the eye to the front bead. This is the typical sighting radius most of us use with the average skeet gun. Slight variations will have minimal impact on the calculation, but if yours is significantly different, substitute your personal sighting radius in the equation.

All skeet fields are laid out such that the distance from the shooter’s eye to the target, as it passes the crossing point 6 yards outside of Station 8, is 21 yards.

We then divide the distance from the eye to the front bead (one yard) by the distance from the eye to the target (21 yards). At this point, we multiply the product of that division by the acceptable deviation of the target from the center of our pattern (8”). The result of that calculation, 0.38”, is the extreme limit of barrel (bead) movement allowable, if the best skeeters are to be successful in maintaining the target within the 20” pattern. Stated another way, the skeeter must repeatedly execute each shot with a minimum barrel-pointing error of 0.38” or 9.7 mm.

By comparison, the front bead on Remington's Model 11 semi-auto (circa 1941) measures 3.5 mm. If a skeet shooter executes a Station 4 shot with more barrel-pointing error than three times the thickness of his front bead at 21 yards, he has introduced an error which will intercept the target with the fringe of the pattern.

So how much barrel pointing error can Dick or our South Dakota pheasant hunter introduce into the execution of their shots under field conditions and still expect to harvest game birds crossing 50 yards in front of the gun? Oh, about 0.18” or 4.5 mm. Just slightly greater than the thickness of the bead on your average field gun. And that’s assuming that all aspects of their gun mount and gun dynamics during the execution of the shot are perfect. I just remembered why I usually limit my field targets to 35 yards or less!

So now you and I have just discovered why this author almost never breaks 25 straight at Original Skeet. That doesn’t mean I will miss the target if I lead (over or under) the bird as a result of a miniscule barrel-pointing error, because there is a reasonable probability that I’ll hit the target with a couple of #9 pellets in the outer ring of the typical 30” pattern. But shooting with that degree of imprecision virtually guarantees that on occasion, the target will encounter a “5-inch patch” in the pattern, and will fly away with its heart shot out! Happens to me during almost every round of skeet. But more to Johnny’s point, the ability of humans to intercept a target on the skeet field with absolute certainty requires more precision than one would imagine. The danger in knowing this, however, is in trying to compensate by being more deliberate in executing your shots. But there are other editors here who are far more capable of telling you how to be precise, without being deliberate. SS

Ron Jones is a retired pharmacist of 49 years who confesses his first love after family and God are shotguns and hunting. His first shotgun experience was his grandfather's 1911 Ithaca Flues 20, and that experience nearly caused him to look for more pleasurable avocations. He admits to missing all 50 targets his father threw with their Remington hand trap, and the experience resulted in a headache which wouldn't quit. But his love for guns, particularly vintage scatterguns, has remained with him in the ensuing 60 years. Our heritage is important. Preserving and embracing the values and traditions which our forefathers have handed down will enrich the experiences of those who follow. In some small measure, Ron hopes to contribute to that body of knowledge the younger generation embraces.