Choke (firearms)

In firearms, a choke is a tapered constriction of the gun barrel's bore at the muzzle end, almost always used with shotguns. The purpose is to decrease the spread of the shot in order to gain better range and accuracy.^[1]

The exit end of the choke is smaller by some dimension than the actual bore of the barrel. This difference is the amount of constriction. Generally the ranges for chokes will be 0.00-1.15 mm (0.00-0.045 inch), while the constriction for turkey chokes may be as much as 2.50 mm (0.10 inch). Choke is measured by the percentage of pellets in the charge that will impact inside a 30" circle at 40 yards (25 yards for "cylinder" and "Skeet1").^[2] Although different choke manufactures have different identification of their chokes, the notches in the chart below are generally accepted.^[3]

Choke	Constriction	Percent	Identification (Notches)
Cylinder	.000	40 at 40 yd 70 at 25 yd	IIIII notches
Skeet 1	.005	45 at 40 yd 75 at 25 yd
Improved  Cylinder	.010	50	IIII notches
Skeet 2 (light Mod.)	.015	55
Modified	.020	60	III notches
Improved Modified	.025	65	II notches
Full	.030	70	I notch
Extra Full	.040	73
Turkey	.045 plus	75 plus

In turkey shoots, a competitor may use his own shotgun (typically 12 gauge) however he likes, and most competitors employ turkey chokes in order to maximize the amount of shot striking the target. Some turkey shoots do not allow chokes for this reason.^{[citation needed]}

A choke is designed to alter the distribution of the shot as it leaves the firearm. For shooting most game birds and clay pigeons, a desirable pattern is one that is as large as possible while being dense enough to ensure multiple hits on the target. Shotguns intended for defensive use often have cylinder or improved cylinder chokes for the widest shot pattern at typically short defensive range.

References

1. ^ shotgun. (2011). In Encyclopædia Britannica. Retrieved February 5, 2011, from Encyclopædia Britannica Online Library Edition: http://www.library.eb.com/eb/article-9067520
2. ^ "Expert Advice". Field and Clays. http://www.fieldandclays.com/expert_chokes.htm. Retrieved January 16, 2010. 
3. ^ "Choke Identification". January 16, 2010. http://www.trulockchokes.com/cgi-bin/eShop/index.cgi?page=choke_identification.htm. Retrieved January 16, 2010.