In the long-gone days of lead shot, choosing chokes for waterfowling was simple: the fuller, the better. A few hunters picked Modified for over-decoy shooting, but more often than not, in those days of fixed-choke guns, you bought a gun with a Full choke, and you never thought about it again. Along came steel, then other non-toxics, and choke-choosing turned complicated. Screw-in chokes were popular by then, too, so you didn’t need different barrels for different loads, just different choke tubes. But now you had—and still have—a variety of different shot types, which perform differently and require different chokes for different situations.
With the understanding that you have to test your own gun with your own chokes and loads to really know how a specific load patterns, here are some guidelines to at least get you to a starting point in your own testing, as well as some general thoughts about shotshells and patterns.
Pellet Size and Velocity
As a rule of thumb, regardless of pellet type, bigger pellets pattern tighter than smaller pellets because they can better overcome air resistance. The faster you drive pellets, the harder they push against air, and the harder air pushes back, which also tends to open patterns.
Practical Patterns
Hunters fixate on high pattern percentages at 40 yards, even when most shots are taken at closer range. Ideally, you want about 75 percent of the shot charge in the 30-inch circle at whatever distance you shoot your birds. That pattern won’t be overly dense in the center and will provide some margin for error with hits in the pattern fringes. This, incidentally, is the “even” pattern people look for.
Buffer Improves Patterns
With soft shot like lead and bismuth, buffer protects pellets from deforming. Deforming pellets are more affected by air resistance, and fly out of patterns. With hard shot, buffer helps pellets flow through the choke more smoothly, also potentially improving patterns.
Pellet Specific Chokes
Several manufacturers offer chokes designed for different pellets, and so named or labeled. Usually they are purpose-named, too, such as “Pass Shooting” or “Timber.” You could do worse than to stop reading this right now and buy some. Aftermarket choke makers know what they’re doing, not just in terms of constriction but also in terms of the internal geometry of the chokes. And, they do a lot of testing. With those thoughts in mind, here are some recommendations about chokes for different pellet types:
Steel
Over Decoys: Light Modified
Long Range: Improved Modifed, or more open with very large pellets
Steel shot is very hard, very round, and not very dense. But you knew that. In general, a choke like Light Modified works well for over-decoy and mid-range shooting. Improved Modified is best for longer ranges. With very large shot, like BBB, some hunters have better success with more open Light Modified and Improved Cylinder, even at longer ranges, because the larger shot flows better through a less constrictive choke.
Bismuth
Over Decoys: Modified
Long Range: Full
While denser than steel, bismuth is soft and brittle. Some pellets will be lost to shattering, although the new generation of bismuth contains more tin than the original stuff, and is much less brittle. As a result, it patterns more efficiently. For over-decoy shooting, Modified is a good choice, and you can shoot bismuth through Full choke for long range. And, because bismuth is soft and brittle, it won’t damage Full chokes.
Buffered bismuth loads, currently available from Boss (their “War Chief” loads) and from Winchester, improve bismuth’s efficiency noticeably. You might get away with less choke with these two, or you might just enjoy putting more pellets on target with them.
HeviXII
Over Decoys: Improved Cylinder
Long Range: Improved Modified
HeviXII is the original HeviShot formulation, which has a density of 12 grams per cubic centimeter. An alloy of tungsten and iron, it is also very hard. It is not round, at all. The pellets are misshapen and sizes within a shell vary. While that should mean poor patterns, it does not work that way with HeviShot. It will pattern tighter than steel loads, and you should back off your chokes accordingly. I’d start with Improved Cylinder or Light Modified and see what you get.
TSS
Over Decoys: Skeet or IC
Long Range: Modified
TSS, a tungsten-iron alloy with the highest possible tungsten content, weighs 18 gr/cc. It is very hard and very round. It patterns very tightly, which has made TSS popular among turkey hunters. TSS also costs several dollars per shell. It’s a shell to save for special occasions or hunts, and you’ll want to choke it properly. The TSS I have patterned printed tight clusters with Modified chokes. Opening up to Improved Cylinder will give you a broad, dense pattern for shooting birds at medium ranges. Modified should work at longer ranges.
Stacked Loads
Over Decoys: Light Modified
Long Range: Improved Modified
Loads combining two different shot sizes and sometimes two different materials are the fad right now. While they are a bit gimmicky, they also work. When the shells combine two sizes of steel, the larger pellets are loaded on top of the smaller pellets. The theory is that the big pellets do a better job of battering through air resistance, and the smaller pellets draft behind them. As a result, patterns are slightly tighter in many cases than you would expect from a one-size load, and, the bigger pellets add energy to the pattern. I tend to use the same choke I would use for regular steel with these, however.
When you mix TSS or HeviShot with steel, the premium pellets are usually much smaller than the steel shot. The smaller, denser pellets fill in the pattern. Results vary. With shells like the original HeviMetal, the pattern percentages are about the same as I would expect with straight steel, so I would shoot my normal Light Modified or Modified.
The TSS and steel loads I’ve shot have put most of the small TSS pellets in the 20-inch core of a 30-inch circle while also filling out the pattern fringes. Light Modified would be a good choice for these. Bear in mind that the purpose of stacked loads is not to have small pellets for close chances and large ones for long range. They are best used within the ballistic limits of the steel pellets. The tungsten or bismuth pellets are there to add extra energy and density to the pattern and make it more effective. For true long-range shooting, I would choose a load of one pellet size and type, say, all HeviXII or buffered bismuth, as the smaller and larger pellets can form longer shot strings at longer ranges.
