COMPETITION CHOKING OF SHOTGUNS
The following are primary considerations in our description of barrel performance:
HEIGHT is the relation of the center of the coverage field to the shooter's line of point. This is a linear measurement and not a measurement of area.
COVERAGE is the area in which adequate shot density guarantees an effective break or kill. It is represented by the diameter in inches of a circular field.
EFFICIENCY is that percentage of the total shot that is present in a thirty-inch diameter circle at a reference distance. The distance depends on the event for which the barrel is being regulated.
YIELD is the percentage of the total shot that is present on a four-foot square (sixteen square feet) target at a reference distance.
RECOIL is only that force felt by the shooter and not necessarily the actual energy in reaction to firing.
COMPETITION CHOKING is both a science and an art; a science insofar as certain principles and practices are constantly valid; an art since replicating mechanical dimensions does not ensure repeating performance barrel-to-barrel. Barrels cannot be choked for optimum performance without test firing and analysis, performing mechanical operations then re-firing, often repeating the steps several or many times. Further, the height, coverage, and efficiency must be related to specific events in a discipline and the shooter's style and ability.
Some of the things which may directly affect barrel pattern performance and recoil perception are the forcing cone (including length, angle or radius of emergence into bore, and finish), the bore (including the diameter, finish, evenness and roundness) the choke or constriction at the muzzle (to include the angle and shape of the conical transition from the bore to the muzzle section, the location of this cone and choke in relation to the actual muzzle, and what occurs between this cone and the muzzle). The amount of constriction of the choke influences muzzle barrel pattern performance, though this influence is not exactly what is widely circulated and generally believed.
To insure the performance optimization of existing quality shotgun barrels, we have hundreds of reamers, cutters, gages, hones, laps, tools and devices, many custom designed. We use no automatic or production tooling, rather completing each operation individual hand work and hand operated machines to ensure each barrel is correctly adapted to achieve the best performance with the shooter, and is therefore Eysterized.
COMPETITION CHOKING: TRAP, SKEET, SPORTING, FITASC, INTERNATIONAL, FLYERS, FIELD AND SPECIALTY. We hone and lap the bore, correctly shape and radius the forcing cone, regulate the height, coverage, and efficiency to the extent this is possible with the existing constriction, choke angle and location of the choke. We must have the entire gun.
RE-BORING: Starting at the back of the bore immediately in front of the chamber and cone, and working toward the choke, we increase the bore to a more optimum diameter. We prefer to work within published dimensions and must consider the barrel thickness as well as how the change influences the balance and handling of the firearm through barrel weight. Backboring can also be a useful tool to introduce additional constriction, or choke, where this may be required. We also may move the location of the beginning or rear of the choke and change the angle of the choke lead, this lead being the cone-ramp connecting the bore and constriction.
Re-boring, coupled with a correctly shaped and radiused cone, gives most shooters a perception of lighter recoil (though the foot pounds of recoil is not affected) , contributes to a balanced performance, and a shorter shot column. These features are a decided aid in optimizing the performance of a barrel. Competition Choking is Required After Re-boring.