Shotgun Bore Diameter and Pattern Performance The most common design in use is the conical parallel. Where the cone stops is the point where the shot exits the choke.ģ- Wad Retarding-They do not have the constriction in the same manner as either of the above designs but instead use bumps or projections to alter the shot pattern. The internal design of chokes can also be broken down into three main groups:ġ- Conical Parallel- This style has a cone that blends into a parallel section which helps to stabilize the shot charge as it leaves the choke.Ģ- Straight Conical- This has a cone only. A popular choke of this type is the Polychoke. To change the degree of constriction you simply remove and replace with a choke of a different diameter.ģ- Adjustable chokes- This style of choke is adjustable throughout the entire range by turning a sleeve, which collapses or allows a collet to expand thus changing the exit diameter. 000 or cylinder.ġ- Fixed chokes- They are made as an integral part of the barrel and cannot be readily changed except by a gunsmith and any alteration is considered permanent.Ģ- Interchangeable chokes- These can be of the “screw on” style which is externally attached or the “screw in” which is recessed into the barrel. Note that many fixed choke barrels marked skeet will actually be. Most, but not all chokes will have an overall length of between 1.5 and 4 inches. The length of the choke can vary as well. In the case of special purpose turkey chokes it can be as much as. 045 thousandths of an inch under bore diameter. As a general rule for standard chokes the total range will be between.

The amount of constriction for a given degree of choke will also vary between manufacturers. For example if the bore of the barrel is. This difference is the amount of constriction. The exit end of the choke is smaller by some dimension than the actual bore of the barrel. A choke is simply a tapered constriction of the gun barrel’s bore at the muzzle end.

Shotgun barrel wall thickness gauge