The smudge just ahead of the three dark dots on the right is the shot cloud travelling to the target. If we could see it every time there would be no need for lengthy treatises on ballistics.
Let’s face it, if we could see the shot in the air there would be no confusion about shotgun ballistics and the arcane secrets of patterning. If shot patterns were visible we would have instant visual feedback of our misses, so as to instantly correct our pointing errors and become good shots fast.
But, shot is not visible in the air, at least not to most of us. Some coaches and some shooters can see the shot in the air. Most of us cannot and we are stumped by our misses. From there it is a short step to pseudo science and arbitrary speculation, to bullistics, a compound word made up from bull and ballistics. Bullistics is expounded by self appointed experts wherever hunters and shooters congregate, physically as well as electronically.
Thankfully some people did real science and have provided some valuable pointers about the behavior of shot patterns from smooth bore barrels.
Three names stand out among the many researchers of smoothbore ballistics, Journee, Lowry and Jones. Each one applied the scientfic method and each one wrote down their methodology and results. And all three show that shotgun ballistics, however complex in terms of pure science, are simple in terms of hitting or missing.
Shot at the patterns plate from a 20 gauge, half choke with Remington one ounce No 6.
In the simple context of hitting and missing the number one factor is shooting technique. Put crudely, a good shot with a crap gun will shoot better than a crap shot with the best gun and cartridge mone can buy. Looking to improve scores via technical gadgetry is no substitute for sound technique.
Naturally ballistics has a role in hits. To paraphrase Greener from his book «The Gun and Its Development», the pattern must have enough pellets, (density), for the size of target shot, the pellets must arrive at the target with sufficient velocity and be of such mass as to impart enough energy to do the job. For these things to happen the shot must be hard enough to retain its spherical shape and fly true.
British gun writer Gough Thomas echoes Greener when he wrote that birds and clays are not hit by guns, they are hit by shot delivered at the proper density and velocity.
The most recent researcher to provide insights into shotgun patterns is Dr Andrew Jones. He has an advantage over previous researchers, instant pattern scans via digital cameras, computers and suitable software. Anyone who has ever counted shot on pattern after pattern appreciates the ability to have the job done by machines!
Dr Jones analysed 2500 patterns he shot himself, and also put through the system photographs of patterns shot in the past. His conclusions reinforce earlier research that patterns behave predictably. The central third of the total shot spread contains roughly 60 per cent of shot. And that happens with all choke constriction at all distances.
Another shot at the same plate, same day, same cartridge, with another 20 gauge, also half choked. This gun cost ten times as much as the one that made the previous pattern. Can anyone tell visually if this pattern is better than the previous one?
No, it does not mean that all patterns are the same. It means that with any choke, at any distance, the central third of the total width and height of the pattern will contain about 60 per cent of the pellets in the cartridge. So, at 40 yards, with improved cyliner choke, the total spread of the shot will be 124 centimeters, 50 inches. The central third will be a circle with a diameter of 41 centimeters, 16 inches. That central third will contain 60 per cent of the pellets.
The same applies to full choke, but in tighter spreads. The total spread of a full choke pattern at 40 yards is 94 centimeters, the central third will be 31,3 centimeters or about 13 inches.
You can work out the total spreads and central cores of patterns all day. The end result is that the way to ensure hits is to place that central core, which measures about a foot in diameter on target. You can hit with the peripheral shot of course. But you cannot depend on the thin periphery to guarantee hits.
Cartridge quality counts in the ballistic equation more than gun quality. A cartridge with efficient wadding that does not allow balling, hard enough shot to prevent deformation, sufficient velocity so as to have enough kinetic energy to break the clay or penetrate game, these are important factors. A quick way to judge cartridges is to pattern them and look for tell tale signs of shot cold welding together, forming «neclaces» of shot on the pattern plate, or worse, clumps of shot that hit like a mini slug. These indicate weldling of shot and in addition to being potentially dangerous due to the increased travel of balled shot, they also thin out the overall pattern.
Rifle target. There is no doubt at all that the rifle-ammo combo that made the group on the top left is the best one. No such visual clues can be gleaned from shotgun patterns regarding the quality of the gun.
Most modern cartridges are well made, from decent components and do not present these problems.
The gun comes last. A smooth bore barrel does not require much to yield the desired pattern. An old article in Gun Digest, titled «Heat it and Beat it» details the formation of crude choking on a single barrel gun via swaging with a conical die. That crude choke printed patterns that conformed to the accepted standards of choke performance.
There will be protests at the notion that a cheap barrel yields similar patterning to a super expensive one. The retort is simple: if shown two patterns, one from a cheap and one from a super expensive best shotgun, can anyone, expert or otherwise, determine which gun shot which pattern by juging pattern quality visually? The answer is No. The same is not true of rifles. A glance at a five shot group, shot from a rest at a pre set distance, usually 100 yards, tells instandly which barrel is the more accurate one. End of debate.
Working at the pattern plate to check on point of aim and point of impact is far more rewarding than trying to find the ideal shotgun load.
Gun quality, when it comes to hitting, is relevant when it helps put the shot where you point. The shotgun should be tested for Point of Aim, to ensure it doesn not have bent barrels. If it is a double it should be printing both patterns to the same POA. After that comes Point of Impact testing. Making sure that the pattern goes where you point and that is where stock fitting comes in. A well fitted shotgun allows you to point it, not aim it, putting the shot where you point. It is also valuable to know how your barrels pattern, to have a mental picture of your patterns.
An interesting note about pointing a gun without use of sights. General Journee carried out tests with army recruits and found that an untrained man had a one degree deviation when pointing a gun. A trained man reduced that deviation by half.
What is one degree of deviation? At 40 yards one degree is 25 iches (the circumbference divided by 360), twice the diameter of that effective central third of the pattern!
The conclusion is that it is better to invest money in shooting lessons, in getting your shotgun tested for POI and fitted for the correct POA than messing around with pattern sheets trying to find that elusive «perfect» pattern. It is also a good idea to take what bullisticians say with a pinch of salt.