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Understanding Shotgun Chokes – A Bird Hunters Guide

shotgun chokes

Exploring the practical application of shotgun chokes in wingshooting

Let me be up front. Grasping the idea of shotgun chokes alluded me for many years. All that was ever explained to me was that the more open the choke, the faster the spread. Simple and accurate — but not helpful when it came to practical application. What I wish had happened was that someone would have said to me, “The choke you should use depends on the distance you are shooting at your game.” Being primarily a woodcock and ruffed grouse hunter, wide open chokes have always worked for me.

However, I never fully grasped the science underlying the reasons behind choosing one choke over another. My reasoning was simple: for fast birds in tight cover, I want the shot to spread quickly. My guiding principle should have been the idea that most birds will be shot between 10 and 25 yards, making the choice of a skeet and IC choke make sense in a double-barrel shotgun.

Before we go any further, let’s investigate the history of shotgun chokes.

The Invention of Shotgun Chokes

Although we can not pinpoint the full story, it is believed that the shotgun choke was invented in Rhode Island in the early- to mid-19th century by a gunsmith, Jeremiah Smith. On July 14, 1868, an inventor from Boston created the first patented “detachable muzzles for shotguns.” These chokes would be screwed on the outside of the barrel and were not fixed. There is some reference to books predating these inventions in Spain; however, little credit has been given toward that history.

On the larger stage, it took the famous W. W. Greener in England to perfect shotgun chokes. Early American versions were inconsistent and patterned poorly. William Greener subjected the theory to many experiments and eventually created the first method that could be consistently repeated. These methods were fixed chokes, meaning it was a permanent part of the barrel design. He is often credited as the inventor of the first shotgun chokes that actually worked.

The claims of how effective the Greener chokes were were put to test in 1875 by the editors of Field Magazine. The classically produced “cylinder” shotguns were outperformed in all categories by the choked Greener productions. This would launch a whole new era and more practical applications of the shotgun in wingshooting.

The idea of interchangeable or “screw-in chokes” did not become a thing until around the 1960s when Winchester produced the Model 1200, the first mass-produced shotgun that came with their “Winchoke” system. From there the science, theory, and application of shotgun chokes has become an ever-evolving world.

Sizes of Shotgun Chokes and Identifications

Shotgun chokes can be a very daunting subject and one that is not always agreed upon. Since the early days of its invention we now have entire companies whose sole business is the production of shotgun chokes. To keep things simple and practical, we’ll explore the classic chokes often applied to wingshooting — starting at the cylinder choke and ending with the full choke.

Note that the measurements of chokes are based on differences. For example, a 12-gauge skeet choke is 0.005 in. (.725 in.) tighter than a cylinder bore (.730 in.). The difference of 0.005 in. is based on the 12-gauge shotgun, which is a .730 in. bore; all differences are referenced from that number. As you will read below, an improved cylinder choke in a 12-gauge is 0.010 in., which is 0.010 in. different than the cylinder .730 in. measurement landing at .720 in.

In other gauges, the measurements are different. For example, a 28-gauge which is a .550 in. bore, would be 0.003 in. different in an improved cylinder. However, we will stay with the 12-gauge example to help more easily visualize and provide a reference point as to how chokes differ from one to another.

Many of these measurements can differ from manufacturer, country, and even history. We made it a point to catch up with Griffin and Howe in New Jersey to confirm with their standards on choke sizing by bore.

It’s also important to note the distance estimates between lead and steel are based on spread and not velocity as lead usually weighs three times greater than steel. Lead is a much denser metal and by default will carry downrange further with higher velocities. However, steel shot spread slower and as a result have denser patterns. This is the reason our charts show greater distance in steel estimates to achieve similar spread patterns to lead.

Cylinder Choke – A cylinder choke is measured at 0.00 in. (.730 in.) and essentially means there is no tapering of the barrel whatsoever. The effective distance for a cylinder choke is out to 25 yards. Past that distance the pattern often becomes too inconsistent and stray to be effective. Some point to the ideal distances being 0 to 15 yards. Steel shot’s ideal ranges from 0 to 20 yards.

Identifying chokes by visual markings (not measurement) can be tricky as there are many versions in place based on country and even manufacturer. We will continue to add to these listings as we discover more systems.

When notches are used to identify a cylinder choke it will appear as IIIII or 5 notches (however, Browning will have no notches). The Spanish identify with 5 stars *****, and the British have no identification maskers as cylinder is considered the “zero” of the measurement.

12 Gauge 0.00″ .730″
16 Gauge 0.00″ .662″
20 Gauge 0.00″ .615″
28 Gauge 0.00″ .550″
.410 0.00″ .410″

Skeet Choke – This choke is often overlooked by traditional media outlets but has a level of popularity in ruffed grouse and woodcock hunting. At 0.005 in. it holds the medium slot between the cylinder and improved cylinder choke. Its best application is between 5 and 20 yards with lead, and 10 to 30 yards with steel shot.

The British have identification markings on this this choke using 1/8. The Spanish and notching systems do not have identifying marks for this choke.

12 Gauge 0.005″ .725″
16 Gauge 0.004″ .658″
20 Gauge 0.004″ .611″
28 Gauge 0.003″ .547″
.410 0.002″ .408″

Improved Cylinder (IC) – Another popular shotgun choke in the ruffed grouse and woodcock world. The practical range is from 10 to 25 yards for lead and 15 to 30 yards for steel. Depending on things like manufacturer and age, an IC shotgun choke for a 12-gauge can range from 0.009 in. to 0.010 in. This variation happens in three chokes related to the 12-gauge, as you will see in the skeet II and modified chokes.

This choke appears as IIII or 4 notches. The Spanish identify them at **** or 4 stars and the British as 1/4.

12 Gauge 0.009″/0.010″ .721″/.720″
16 Gauge 0.007″ .665″
20 Gauge 0.006″ .609″
28 Gauge 0.005″ .545″
.410 0.004″ .406″

Light Modified (LM) or Skeet II – The light modified choke is not as popular as it rarely becomes standard issue in interchangeable chokes with mass-produced shotguns. Landing at a measurement of 0.012 in. to 0.015 in., its practical application is for ranges of 15 to 30 yards with lead and 20 to 35 yards with steel shot.

These chokes do not have identifying marks from any of the referenced systems.

12 Gauge 0.012/0.015″ .718″/.715″
16 Gauge 0.010″ .652″
20 Gauge 0.009″ .606″
28 gauge 0.007″ .543″
.410 0.006″ .404″

Modified (MOD) – The modified choke is most effective from 20 to 35 yards with lead and with steel shot at 25 to 45 yards. In a 12-gauge, its measurement can be 0.019 in. and 0.020 in. (or .711 and .710 in).

Represented by III or 3 notches, 1/4 by the British, and *** or 3 stars by the Spanish.

12 Gauge 0.019″/0.020″ .711″/.710″
16 Gauge 0.015″ .647″
20 Gauge 0.014″ .601″
28 Gauge 0.012″ .538″
.410 0.008″ .402″

Improved Modified (IM) – The improved modified is designed for targets at 25 to 40 yards with lead and 30 to 50 yards with steel. Measured at 0.025 in. on a 12-gauge shotgun.

It will appear as II or two notches. The Spanish use ** or two stars. The British mark as 3/4.

12 Gauge 0.025″ .705″
16 Gauge 0.020″ .642″
20 Gauge 0.019″ .596″
28 Gauge 0.016″ .534″
.410 0.011″ .399″

Full Choke – It is important to reference that there is such a thing as a light full choke. However, its popularity has never really taken off. Therefore, the full choke is actually 0.010 in. greater than the Improved Modified at 0.035 in. Its effective range is 30 to 45 yards with lead. It’s very important to understand steel shot, in some cases, cannot be shot through a full choke, although it is widely debated that higher quality manufacturing will allow for the use of steel. But some still argue that patterns are inconsistent with steel and full chokes. Luckily for us upland hunters, the use of a full choke does not have much practical application in the field. We can leave that guessing to waterfowl hunters . . .

The full choke is one notch (or I), 1/1 according to the British, and one star (*) to the Spanish.

12 Gauge 0.035″ .695″
16 Gauge 0.028″ .633″
20 Gauge 0.025″ .590″
28 Gauge 0.022″ .528″
.410 0.015″ .395″

How to Apply a Choke to Your Situation

We have worked to provide a series of articles tackling the practical application of shotgun choke sizes based on upland game. We’ve covered such choke applications for birds like the chokes for pheasant, chokes for ruffed grouse, and chokes for bobwhite quail. Some of those articles will suggest a switch in shotgun choke based on seasons. For example, early season ruffed grouse results in much closer shooting than later in the season when the leaves are down. To put it simply, you should consider the average distances you shoot at whatever upland game you are pursuing and then apply the distances above. On days where birds are more jumpy, you may want to consider going to a tighter choke for longer shots.

Choke Size Lead Steel Shot
Cylinder 0 to 15 Yards 0 to 20 Yards
Skeet 5 to 20 Yards 10 to 30 Yards
Improved Cylinder 10 to 25 Yards 15 to 30 Yards
Light Modified 15 to 30 yards 20 to 35 Yards
Modified 20 to 35 Yards 25 to 45 Yards
Improved Modified 25 to 40 Yards 30 to 50 Yards
Full 30 to 45 yards – – –

We Should Pattern Test Our Shotguns and Chokes

It’s also important to consider that not all chokes and shot mixed together are created equal. A No. 6 bird shot through a Beretta over-and-under with modified choke might pattern differently than the same size choke and shot size combo in a different brand. That applies to different brands of shotgun shells, chokes, wad types, and even the shotgun themselves.

Testing on paper to see at what distances a 30 in. circle has an effective pattern should be part of our pre-season routines. It’s popular consensus that once less than 60 percent of the shot appears in that 30 in. circle, the shot is no longer effective at that distance. Exploring brands and combinations to find what the idea scenario is for your application should be part of the routine for all of us.

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