This chart will give an idea of what choke to use at what yardage for sporting clays... with the caveat that ammo, intended target, angle of presentation ( front, back, side ) also weigh in on the equation...
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Red - Pattern too small | Yellow - small but usable | Green - Optimal Pattern
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Choke Tube Selection:
Choke tube selection is a confusing issue amongst a lot of shotgunners but one that is easily explained.
The real reason you want the right choke is to be able to place at least 70% of the shot in a 30" circle at 40 yards... the minimum / maximum pattern kill zone... meaning the pattern will cleanly kill anything in this circular zone.
Selecting the correct choke tube is nothing more than moving that same exact pattern to different yardages. In other words... if you want to shoot at a target 20 yards away then select a choke tube that gives you 70% of the pattern in a 30" circle at 20 yards...same if shooting at a target that is 45 yards away, select a choke tube that will give you 70% of the pattern in a 30" circle at 45 yards.
Extra Full Choke: ...................delivers a 70% pattern at 45 Yards.
Full Choke: ............................delivers a 70% pattern at 40 yards.
Modified Choke: ....................delivers a 70% pattern at 35 yards.
Improved Cylinder Choke: ....delivers a 70% pattern at 30 yards.
Cylinder Choke: ....................delivers a 70% pattern at 25 Yards.
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