The first mallard I killed this year set the pattern for the season. It flew in with a small flock from the estuary to the south. It responded to my high ball and tilted toward the decoys in front of my blind. I knew that the smaller shot wouldn't have an extended kill zone, so I kept my head down as the duck moved closer. Then, just as it began to flare, I rose and shot. The mallard folded and tumbled. Lily didn't even have to swim for it. Over the next several months, most of the birds I hit fell immediately, and many had between four and seven pellets in them when I cleaned them.

Clearly, I had finally arrived at the solution for my type of shooting and the gun I prefer to hunt.

But there are many other situations where this arrangement would perform as poorly as the 2s of steel had.

SHOTGUN SHELL THEORY
You don't need to memorize ballistics tables or powder formulas to choose the best shell for a gun and the way they hunt. However, it is important to keep two facts in mind: 1) a pellet traveling faster has more energy (that is, killing power) than the same shot at a slower speed, and 2) heavier shot retains energy farther than lighter shot.

In other words, a load of size 4 shot will hit a duck harder at 40 yards than a load of No. 6 shot with the same amount of shot and powder. This would seem to argue for the use of heavier pellets in virtually all situations. But it isn't that simple, because shells with larger shot hold fewer pellets than smaller shot, and research has shown that a duck the size of a mallard must usually be hit by at least four pellets to be cleanly killed.

The choice of a shell, then, becomes a compromise between how hard the pellets hit the bird and the density of the shot pattern.

In the days before lead was outlawed, shell selection was relatively straightforward. Most hunters who shot ducks over decoys favored size 4 or 5 shot, and goose hunters preferred 1s or 2s, often in magnum loads. These shells were good compromises between punch and pattern density, and they accounted for lots of birds. However, steel is only about 70 percent as dense as lead (in this context dense means heavy, not how thick the pattern is), and hunters quickly discovered that it was much less effective than lead in comparable loads, especially at a distance.

To compensate, waterfowlers were advised to switch to a shot two sizes larger -- a 2 in place of a 4, or a BB in place of a 1. But as we have seen, bumping up the pellet size reduces the amount of shot into a given length of shell.

Magnum loads were available long before the steel shot requirement, but they became much more popular after lead was prohibited. Magnums contain more powder and more shot than standard loads, but the word "magnum" is more of a marketing device than a ballistic term, and any load over 1 1/4 ounces can be considered a magnum if it is that company's heaviest shell in that configuration. Moreover, contrary to conventional wisdom, magnums are not necessarily faster nor do they produce more energy than standard loads. The thing that makes magnums effective is that their patterns are fuller (denser) and they can push heavier shot, and this significantly increases the odds that four or five pellets will hit the bird at longer, reasonable distances. The downside of magnums is they can't be used in many older weapons.