Understanding shotgun chokes and patterns would be a whole lot easier if we could just see exactly what it is we are talking about.

The problem is, we can't. We can't see a pattern of shot while it is in the air, and even if we could, what we saw one nano-second would be changed significantly a nano-second later and no longer in existence, in any form, a second after that.

This fact, more than any other, has fed the lively arguments over chokes, shot sizes, forcing cones, and myriad other changeable factors in shotgun shooting virtually from the time choke was invented in the 1870s.

Although Americans like to think choke was invented by Fred Kimble in 1868, the idea showed up two years earlier in England, patented by gunmaker William Rochester Pape. We can be charitable and assume that Kimble happened on the idea independently, albeit after Pape.

Today, the notion that patterns can be improved by constricting the muzzle of a shotgun may seem so obvious that it's a wonder it wasn't hatched the day after the first load of shot was fired, but that is true of so many things. The wheel, for example. What could be more obvious? But look how many cultures never invented it at all.

The concept of choke has been refined considerably since Pape's day. Early guns had one barrel marked "Choke," denoting a constriction of about .035 inch, and one barrel left unmarked since the alternative to Choke was nothing at all. It was more or less Cylinder (Cyl.), with a constriction of maybe .002 to .005 inch, but early guns were not marked as such.

In England, gunmakers went on to refine choke to degrees measured in fractions--1/4, 1/2, and 3/4. In America, we developed Improved Cylinder (IC) and Modified (M) as the rough equivalents of 1/4 and 1/2. Later, Skeet #1 and #2 were developed purely for skeet shooting, and these constrictions lay between Cyl. and IC.

With the advent of interchangeable choke tubes in the 1980s, makers began to refine the divisions farther and farther, splitting hairs and then splitting them again. Eventually, some marked the constrictions in thousandths, with one tube marked .010, another .015, and so on. Other than adding to the confusion, such divisions have little real impact on how well a shotgunner is likely to do on any given day, whether he is shooting sporting clays, doves over a sunflower field, or woodcock in thick cover.

If you center your pattern on your target, it will make no difference whether your choke is Cylinder or Full. None. However, this does not head off the endless arguments over what choke is appropriate for what use, and that brings us back to the problem outlined above: We cannot see exactly what it is we are arguing about, and so we are free to imagine what happens and then propound that point of view.

Shot Pattern Analysis
The traditional method of measuring a shot pattern is to put up a sheet of paper at 40 yards, fire a load of shot at it, then draw a 30-inch circle around the greatest concentration and count the pellet holes. Relative choke is determined by the percentage of pellets inside the circle compared to the number in the original shot charge. An ounce of #7½s contains 345 pellets; if 242 pellets fall within the circle, that is 70 percent, and hence a Full choke.