.... April 2005 ~~~~ Editor:  Cliff Hanger ~~~~

Choking the Shotgun by Old Scout

   First grasp the shotgun in both hands and squeeze hard…………Oh wait, we are talking about choke boring of the shotgun barrel! I think most shooters are aware that shotgun barrels generally have some degree of choke, and that “choke” is a constriction of the barrel at the muzzle. 

   Lets take a closer look. History, at best, is pretty clouded, but it would seem that choke bored shotgun barrels were developed at much the same time by an American Fred Kimball, and the well known English gun maker W.W. Greener. These gentlemen started experimenting with choke about 1870, and by 1875 choke boring was the talk of the day at most gun clubs. 

   The basic purpose of choke is to control the size of the shot pattern, and thereby the effective range of the gun. As the shot charge leaves the muzzle, air resistance causes the pellets to start spreading out. 

The cylinder bored gun expels the shot in one “Glob” (  a good scientific term ) and nearly all the pellets are acted on by air resistance, causing a rapid expansion of the shot pattern.

   On the other hand, the choked barrel, that is one having a constriction at the muzzle, will squeeze the shot charge and expel it as a “Squirt” (another of those scientific terms). As the elongated shot charge travels through the air, the front pellets are acted on by air resistance,  while the pellets toward the rear of the column are not so effected. The result is many more pellets stay close together, and impact the target in a smaller area, making a smaller “Pattern”.

   Figure 1, shows by high speed photography, this effect. Figure 2 depicts the various methods of manufacture used to produce a “Choke”. Chokes are made in varying degrees, “cylinder” being the least choke and “extra full” being the greatest amount of choke. The manner of defining the degree


Cylinder Bore
4 feet from muzzle

Full Ckoke

True Cylinder

Bored Choke

Conical or American Choke

Recessed or Jug Choke

Swaged Choke
of choke, is to list the percentage of the shot charge that strikes within a 30 inch circle at a range of 40 yards. A number of standard degrees of choke have been settled on by industry, and given names. Listed below are the various levels of choke, from smallest pattern (tightest choke) to largest pattern (no choke). 
Extra-Full (or Turkey Choke)
Full Choke                                Improved-Modified Choke
Modified Choke 
Sheet-2 Choke 
Improved Cylinder Choke 
Sheet-1 Choke 
Cylinder Choke (no choke)
For Cowboy Action Shooting , choke is not really your friend. At the short range we use our CAS “scatterguns”, patterns are very small, on the order of 8 to 18 inches at 8 to 10 yards. If you bring Grandpa’s ole full choked ’97 to a match, you’ll find the patterns at close range so small that you must actually “aim” the gun. That takes time, slows you down, and may lead to misses. Shooting a cylinder bored gun in CAS is not, in my opinion, a handicap. I use Improved Cylinder choke in my guns.

   With the advent of the screw-in choke tubes, today’s shooter has the option of trying different chokes. The screw-in tubes are not very expensive. They also are not very strong! If you have had your shotgun fitted with screw-in choke tubes, or purchase a gun with tubes, take a close look at the installation before firing the gun. When installed in the barrel, the lower edge of the choke tube must be below the surface of the bore. It is not uncommon to have choke tube blow out of the barrel if not installed correctly.

Old Scout

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