What are shotgun patterns?
Patterns are normally expressed with a name such as improved cylinder or as a percentage such as 50%. The patterns are always assumed to be measured at a distance of 40 yards. The exceptions to this are cylinder bore and skeet 1 chokes in all gauges and .410 bore shotguns in all choke sizes. These are measured at a distance of 25 yards. The following chart can be used as a general guide. Name #% Constriction Cylinder Bore 40 .000 Skeet 1 50 .005 Improved Cylinder 50 .010 Skeet 2 55 .015 Modified 60 .020 Improved Modified 63 .025 Full 65 .030 Extra Full 68 .040 Super Full 70 .045 Turkey 70+ .045+ The above chart is based on using premium field loads with #8 shot. Generally the larger size of shot you use the less degree of choke is needed to get an equivalent size pattern. High velocity or magnum loads normally do not pattern as well as lighter loads. The same load by different ammunition manufacturers may not pattern the same. As you can see, there are many things that can cause a shot
