Much has been said and written about which chokes to use on which targets to get the best result: that ball of dust when the clay is well and truly busted! With the many choke options available today, it is worth revisiting the subject. It is also worth remembering that the target presentations of each particular game—sporting clays, skeet, trap, FITASC and so on—will have an influence on the chokes chosen.
The History of Chokes
Englishman W.R. Pape is often credited with the invention of the choke in 1866. However, Sylvester Roper, an American gunsmith, actually patented the invention of choked barrels in April that same year several weeks prior to Pape receiving his patent.
The following year American Fred Kimble also claimed to have invented the choke. And to add to the confusion, in 1874 W.W. Greener, another Englishman, developed the choke even further.
In the end, whoever is responsible, the concept of choke has done more to increase the range and pattern of the shotgun than any invention since.
How Choke Works
Choke creates a tightening effect in the barrel of a shotgun. As the walls of the barrel are parallel from the chamber toward the muzzle, choke gradually increases the wall thickness of the barrel, decreasing the inside diameter at the muzzle.
The amount of choke constriction is measured in thousandths of an inch added to the nominal boring of the barrel. Before the invention of choke, all barrels were simply straight tubes, hence the expression “True Cylinder”—the most-open barrel having “0,” or no, choke. Choke constriction is measured in increments of .010", with the tightest, or Full, choke measuring .040". (Today there are some Extra Full turkey-type chokes measuring .045".)
Range & Distance
In general, the more choke in the barrel, the greater the shotgun’s effective range. With more constriction, when the shot column leaves the barrel, it is narrower and more air resistant and the amount of spread is reduced. That said, it is a delicate balance, as with larger pellets it’s possible to have too much constriction, resulting in less-than-optimal patterns.
The accepted optimum ranges of different chokes for putting pellets in a 30" circle are:
• 40–50 yards plus: Full
• 35 yards: Improved Modified (Three-Quarters)
• 30 yards: Modified (Half)
• 25 yards: Improved Cylinder (Quarter)
• 20 yards: True Cylinder or Skeet
You can see that for most shotgunning a True Cylinder choke would be of little use at 40 yards and, conversely, a Full choke little use at 20. Of course, chokes pattern differently with different loads and shot sizes, so the only real way to tell optimum range is through pattern-testing.
Further Choke Developments
Because chokes have such a major impact on the effective range of a shotgun, many variations and permutations have been created to enhance their effectiveness.
E. Field White, the inventor of the Poly-Choke, had several designs patented; as did Col. Cutts, inventor of the Cutts Compensator; and W.R. Weaver, inventor of the Weaver choke. Many manufacturers have tried different choke designs, including swaged, conical, recessed, cylindroid-conical, bell, trumpet, retro and Tula, to name a few.
But it was Winchester’s introduction of the first internal multi-choke, the Winchoke, in 1959, that had as much impact as the development of the choke itself. Although a similar concept had been tried by Sylvester Roper, it was Winchester’s multi-choke system that would change the game of sporting clays and upland wingshooting.
In the 1960s and ’70s with the “new sporting clays,” many clays enthusiasts carried two guns: a skeet gun with more-open chokes for close shots and a trap gun with tighter chokes for longer shots. At the time this was the only way they could shoot the gun best choked for a particular target presentation. The Winchoke was the first internal, screw-in, interchangeable choke offering a selection of chokes for a variety of distances, allowing a competitor to carry only one shotgun.
The Winchoke was soon followed by an invention by Jess Briley of Houston. Briley came up with the aftermarket screw-in choke, so any shotgun could have its barrel(s) machined and threaded to accept the choke—thereby allowing the choke to be adjusted to suit the target. This allowed greater flexibility so that one shotgun could be used for the field and then completely transformed into a clay-target gun.
The Briley System is now an industry standard and is factory-fitted in many shotguns. Other specialist companies offer retrofitting to fixed-choked guns, or they can adapt and install their own systems to replace the manufacturers’. In the US Briley, Rhino and Seminole are suppliers of these specialist choking services. In the UK Nigel Teague has built a reputation of success with his choking system for both game and clays.
Because these aftermarket installations have given greater flexibility to choke selection, shooters are now able to install finer degrees of choke—such as Light Modified (.015"), which is halfway between Improved Cylinder and Modified and is a good choice for semi-automatic (single-barrel) shotguns.
Multi-chokes are interchangeable tubes that are screwed into a shotgun’s muzzle(s), allowing customization based on the situation. They come in several types, including flush-fitting chokes, which have castellations to facilitate installation and removal with a key or wrench; extended-tube chokes, which are knurled and put in and taken out by hand; wad-stripping chokes, which are designed to strip off the wad upon firing in order to open the pattern more quickly; and ported chokes, which some feel reduce muzzle flip and recoil.
Once chokes were developed, it was quickly learned that the more gradual the lead in to the constriction (the forcing cone), the fewer pellets are deformed when passing through it. Today’s specialist choke makers have refined their products to minimize the deformation of shot. Modern chokes, whether parallel or gradually tapered, are much longer than the early Victorian versions.
Choke Affects Air Resistance
As shot leaves the barrel, it encounters air resistance. The loud Bang! heard when a shot is fired does not all come from the exploding powder; it is also the sound of the shot stream breaking the sound barrier.
This air resistance slows the shot stream and forces the component pellets apart. The deformed pellets, or “flyers,” peel away first, and then the outer layer of pellets stretches into a shot stream in a three-dimensional “tadpole” shape. This shot stream provides the margin for error that enables us to shoot moving targets. But the shot stream needs to be balanced; if it is too thin, there will be gaps large enough for the target to pass through untouched.
Choke Choice Matters
It is key to choose the appropriate choke for the distance at which the target will be broken. A slightly tighter choke than the distance appears to call for will deliver a denser shot stream with breaking capabilities along its entire length. This is preferable to using a more-open choke and depending on a wider, longer shot stream that will be full of gaps.
With so many choke options available today, it is definitely worth taking the time to experiment as well as to confer with your shooting partners. Everyone will have an opinion, and everyone will have had different experiences with different chokes. In the end, the most reliable way to determine which chokes are best is to pattern-test your shotgun using different choke-and-cartridge combinations at different distances. Only then will you truly know the optimum combination of choke and cartridge for your particular shotgun.
Chris Batha’s most recent book, The Instinctive Shot, can be ordered by visiting chrisbathashooting.com, which also includes schedules of shoots and clinics with the author.
I recently purchased a new doublegun which appeared to throw patterns more open than the choke constriction marked on each tube. Upon closer inspection, I discovered that the points of constriction in each tube were about one degree of choke less than is required for each choke designation. The bore diameters measure 0.620 inch. References suggest 6 additional points of constriction for each successive choke. The skeet choke is actually over bore by 0.003 inch, and the IC, Mod. and IM chokes provide 3, 6, and 12 points of constriction respectively. My solution was simply to use the IC choke at skeet range, the Mod choke for IC range, and the IM choke for Modified range targets. I’m happy with the results.