Generally speaking: choke is the constriction built into the barrel at the front end that determines the spread of the shot column at varying distances. Generally also, the percentages of shot in a 30inch circle at 40 yards is the basis for describing choke. 70% in the circle is considered "Full", 60% is "Modified", and variously from 40-50% ranges from Cylinder to Improved Cylinder. Skeet is shot at nominally 20 years and you want an open choke (cylinder) for such work. Conversely, for ducks at 40-50 years you would want a Full choke. Think of the nozzle on a garden hose...the more you constrict it the farther it shoots out and the narrower the spread. As you "open" up or deduce the constriction the wider the spray and the shorter the distance. Refer to Bob Brister's book entitled "Shotgunning, the Art and the Science."
January 9, 2003, 06:39 PM
Colt, I imported a couple threads on chokes into the floating thread on the top of the page. I think they'll help you a bit.
The guys have it, but let me nail it down...
Choke is a funnelling, or lack of same, in the barrel at or near the muzzle which acts to control the pattern,affecting spread at any given distance.
It's measured in thousandsths of an inch. ,040" is about the tightest used, and is considered Full or Extra Full, depending on who you ask.
0 constriction is called Cylinder bore, because the bore(once past the forcing cone in front of the chamber) forms a cylinder. It forms a good pattern closer, say 20 yards, while full will in theory give a similar pattern at 40 yards.
January 10, 2003, 11:28 AM
My thanks to each of you for your quick and helpful replies:)
January 12, 2003, 08:26 AM
And I must add that your pattern is what you actually want to acheive - a certain amount of shot in a defined area.
Choke matters, but too, so does type, quantity & hardness of shot (besides shot cup, buffering stuff, etc.)
Quick example = steel #4 may shoot quite a bit tighter in a modified choke than will the same load using lead shot ....
Only way to really tell what kind of pattern you'll get is to shoot that load out of your gun using that choke. May have to play with that some to arrive at what you want.
Likely mentioned, but didn't see it is yup, chokes can be changed on most modern shotguns. Just a front-end screw-in thing.
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