While there are a variety of choke types, I'm going to limit
this post to the five most common: Cylinder, Improved Cylinder, Modified, Improved
Modified, and Full. Each of these types has a specific constriction with a
predictable effect on shot pattern at different ranges, and therefore best use
conditions.
Choke Constriction
The concept of choke in shotgun barrels is quite old and, once understood, is fairly simple. Put plainly, a choke is a tapered constriction near the end of a shotgun barrel which is designed to slightly compress the shot column and delay the spread of pellets. The tighter the choke, the greater the amount of compression (relatively speaking), which provides a corresponding improvement in effective range.
- Cylinder Bore: 0 inches (no constriction)
- Improved Cylinder: 0.010"
- Modified: 0.020"
- Improved Modified: 0.025"
- Full: 0.030"
Cylinder Bore, which applies no constriction,
is best for close range applications such as a home defense shotgun.
Improved Cylinder is
preferred for trap and skeet shooting, though if longer shots are needed, Modified may be a better choice.
For bird hunting, Modified and Full are the
most common options, depending on range.
Choke Ranges
Being able to accurately judge distance is one of the most important factors whether bird hunting or shooting clay pigeons. Most people have a hard time with this, causing them to shoot either ahead of or behind their target. To quote Bruce Bowlen, author of The Orvis Wing-Shooting Handbook:
“My experience as an instructor has led me to believe that most shooters tend to use too much choke rather than too little,” he said. “This is directly related to most folk’s tendency to overestimate range… and is particularly true when the targets are overhead.”
While there are many variables such
as pellet size, wad performance, and power, the generally accepted optimal
ranges for the different chokes in a 12 gauge shotgun using lead shot are as follows:
- Cylinder Bore: 0 to 20 yards
- Improved Cylinder: 20 to 30 yards
- Modified: 26 to 42 yards
- Full: 30 to 50 yards
Improved Modified choke distances fall
somewhere between modified and full.
Lead vs Steel Shot
Even though lead is banned for many types of hunting, it's still the standard used for determining distance. If you are using steel shot, be aware that there is a performance difference between lead and steel due to relative mass, so it is advised to go up one or two shot sizes when using steel shot to achieve similar performance.
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| https://forum.cartridgecollectors.org/t/shotshell-shot-size-table/36689 |
Never use a full choke with steel shot! The excessive constriction can damage the muzzle of the shotgun. In fact, when shooting steel shot you should always use a more open choke than you would with lead in order to widen the pattern.
Fixed Chokes
Some shotguns come with a fixed choke which cannot be changed short of swapping out barrels. While fixed choke barrels may have marks at the muzzle, it is more likely they will be marked near the breech with the other barrel markings.
Choke markings from top to bottom:
Winchester 1897; Remington Model 11; Mossberg Model 500
Winchester 1897; Remington Model 11; Mossberg Model 500
Removable Chokes
Many removable choke tubes are identified by the use of notches
at the muzzle end, so choke type can be identified quickly and easily.
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Removable Choke Markings
- Cylinder (no choke): IIIII (5 notches)
- Improved Cylinder: IIII (4 notches)
- Modified: III (3 notches)
- Improved Modified: II (2 notches)
- Full: I (1 notch)
For easier installation and removal of threaded choke tubes,
choke wrenches of various types are available. They range from a simple stamped metal card to fancier crank driven systems.
Hopefully this article has helped you to understand the different chokes
and their effects on shot pattern.
Good luck, and safe shooting.
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