More about Choke

Choke is a constriction near to the muzzle of a shotgun intended to alter the trajectory of the outer pellets of the shot load, creating a denser, more concentrated pattern. Almost all degrees of choke will produce more concentrated patterns than a true cylinder, but not necessarily better patterns. They may be tighter, but can be patchy, leaving gaping holes with little or no pellets. We specify choke by the amount of barrel constriction; that is the difference between the barrel diameter and the muzzle diameter. In England chokes are described in the table below.

US choke tube manufacturers have unnecessarily complicated this, coming up with 12 variations!

Briley Choke Tube Designation

What do we mean by a Full Choke pattern?
Patterns must be measured by their density, not by the choke constriction that produced them. For centuries the accepted pattern density is measured at 40 yards and compares the number of pellet in a 30 inch circle with the number of pellet in the load.

None of this means that a gun or screw-in choke marked "Half" or "Full" by the manufacturer will deliver Half or Full choke patterns. Even if it does, it is highly unlikely that it will continue to perform consistently when used with other loads.

In 1998 BASC produced and enlightening document, entitled "SHOTGUN CHOKES AND PATTERNS", comparing patterns using various shot sizes and materials. It shows that patterns with steel shot benefit from light choking, but fail to improve with heavier choke. From our experience Tungsten Matrix suffers the same fate. Tungsten-iron shot, such as Hevi-shot or Power Shot, on the other hand, responds well to heavy choking, with 3.5mm diameter shot performing better that 3.0mm diameter.

What else can affect patterns?
Primer and Powder - High initial shock can weld and distort pellets.
Wadding - Poor sealing allows gases to escape and causes turbulence.
Pellets can be lost, become imbedded in soft wads.
Less pellet deformation if wad protects the shot from the barrel.
Shot - Size, density, malleability, finish, roundness and elasticity all affect pattern.
Buffer - Can protect shot from deformation and generally tightens patterns.
Cartridge closer - It is generally accepted that card closures interfere with pellet trajectory.
Chamber Length and Diameter- Ill fitting cartridges allow gases to escape.
Chamber forcing cone - Can distort pellets.
Barrel length, diameter and finish - Pellet damage and escaping gases.
Almost everything in fact!

What is good for better patterns?
A progressive powder that accelerates the shot throughout the barrel.
Wads with a good gas seal, and that protect shot from barrel.
Hard, round, dense shot.
Shot Buffer.
Crimped closure.

So what choke should I use?
Use our Ballistic Calculator to get a rough idea based on your cartridge, your quarry and the range you want to shoot. Then go out and pattern your gun to see if practice lives up to theoretical expectation!