A duck hunter from Illinois named Fred Kimble is credited with the invention of the choke tube back in 1866. However, the idea of a choke tube did not start to slowly catch on until around 1959 when Winchester produced their Model 59 with a Versalite choke system. Eventually manufactures started to produce and tweak choke systems into what we have today.
Choke tubes are small tubes, usually a few inches long that constrict the disbursement of shot as it exits the barrel. The way choke is determined is by subtracting the diameter of the bore of a choke tube from the diameter of the bore of the barrel. Let’s say the diameter of the inside of a 12 gauge barrel is .720, and the diameter of the choke tube is .700. That is a .20 of an inch constriction of the shot as it exits the barrel which makes this choke a “Modified” choke size.
The chart below shows the diameter of the many different size chokes.
| CHOKE SIZE | 10/12/16/20 GAUGE | 20/410 GAUGE |
| Cylinder | .000 | .000 |
| Light Skeet | .003 | .003 |
| Skeet | .005 | .005 |
| Improved Skeet | .007 | .007 |
| Improved Cylinder | .010 | .009 |
| Light Modified | .015 | .012 |
| Modified | .020 | .015 |
| Improved Modified | .025 | .018 |
| Light Full | .030 | .021 |
| Full | .035 | .024 |
| Extra Full | .040 | .027 |
| Super Full | .050 | NA |
This chart shows the percentage of shot that is placed inside of a 30” circle fired from various distances indicated in the three columns.
| CHOKE SIZE | 20 Yards | 30 Yards | 40 Yards |
| Cylinder Bore | 80% | 60% | 40% |
| Improved Cylinder | 100% | 77% | 55% |
| Modified | 100% | 83% | 60% |
| Improved Modified | 100% | 91% | 65% |
| Full | 100% | 100% | 70% |
What does all of this mean? A tighter choke, “Full” for example, will keep the pellets in a tighter pattern as opposed to “Cylinder” which will spread the shot pattern out. A Full choke would be used for making a long distance shot; since the pellets are grouped tightly they will travel farther and keep more pellets in the kill zone. A Cylinder choke will quickly spread the pellets which will provide good coverage of pellets in the kill zone for close shots.
