Calling ducks close enough so they present good shots can be difficult. So can killing a bird that in some cases flies more than 30 miles per hour. And recovering a downed duck with a dog often is the result of years' worth of training.

All are part of the challenge of duck hunting.

But perhaps nothing is as challenging in waterfowling, and as mysterious, as matching a hunter to a shotgun that fits him or her, and choosing the gun choke and shotshell that gives the hunter the best chance to kill ducks cleanly.

This process has become more complex since the advent in recent decades of nontoxic (primarily steel) shot. First offered for sale in the 1970s, steel or other nontoxic shot is now required for duck and goose hunting, replacing lead, whose use in waterfowling dates to the 16th century.

Lead shot, scientists have demonstrated, harms wildlife and the environment in various, serious ways.

Changes abound

But which steel shot loads work best for ducks and which chokes? That question is often on the minds of waterfowlers, especially after they miss a shot they thought they should have made.

The fact that steel and other nontoxic shotshells are continually being refined is one factor to consider. Shotshell manufacturers, like other manufacturers, are forever trying to improve their products, and changes they make, year to year, can affect performance.

Hunters who fail to regularly pattern their shotguns won't be aware of these changes.

My interest in all of this was piqued after reading a column in Field and Stream magazine by Phil Bourjaily that examined the performance of different shotshell loads fired at various distances through the same gun, using various chokes.

His conclusions, in a nutshell: You'd best pattern your gun to see how different load and choke combinations perform. And it might be a good idea to use a different load in the chamber of your shotgun (for relatively closer shots) than the two rounds (often for longer shots) held in your gun's magazine.

Curious about my shotgun's performance, I called a friend, Wisconsin firearms safety instructor Brett Bader, and he and I blasted a bunch of holes through targets the other morning, testing different shotshells at 25 and 35 yards, using two chokes -- modified and improved cylinder -- in my Browning Maxus 12 gauge.

Our finding: The waterfowler who limits himself to shots of 25 yards or less will kill more birds -- probably a lot more -- than the hunter who fires at ducks (or geese) flying 35 yards or farther away.

Brett and I began by testing two 3-inch shotshells -- 1 1/8-ounce Winchester Xpert #3 and 1¼-ounce Federal Black Cloud #3 -- fired at 25 yards. Through modified chokes, both rounds provided excellent coverage.

About half the cost

Changing to improved cylinder chokes, both shells again provided adequate concentrations of pellets within 24- and 30-inch circles to cleanly kill ducks (or geese). (Federal, I'm sure, would argue the Black Cloud would kill comparatively more cleanly than the Xpert because of the irregular shape of Black Cloud FlightStopper pellets and because the pellets are delivered with more down-range energy.)

On the other hand, the Xpert loads cost about half what Black Cloud costs, about $10 a box to about $20.

Shooting both loads at 35 yards, the patterns opened up significantly, and differences emerged between the two. Bourjaily, in his column, advised that to kill big ducks such as mallards, a minimum of 90 pellet strikes are needed in a 30-inch circle.

Assuming that measure is correct (though I believe a more accurate standard, particularly with steel, is 24 inches), the #3 Black Cloud delivered a lethal load (though not as lethal, measured by pattern density, as at 25 yards), while the #3 Xpert fell somewhat short (switching to #2 loads of Xpert at 35 yards delivered better patterns).

My conclusion, again: Regardless of shotshell used, the best chance a hunter has to kill ducks cleanly with steel loads is to take shots of about 25 yards or less. Beyond that range, tighter patterning (and more expensive) loads might be best to have in a shotgun magazine, among them No. 2 Black Cloud, No. 2 Winchester Supreme High Velocity, some variety of Hevi-Shot (about $3 per shell) or similar shells.

Dennis Anderson •