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That is, in order to have the same number (not percent) of pellets in the inner 20-inch core of the pattern, does the 28 gauge need, for example, a full choke when a 12 gauge might use an improved-cylinder to get the same number of pellets in the pattern core ?
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Increased choke gives you a hot core. If you start out with less not sure how you could get it done any other way than be using more choke. Given the use of the same size shot and shell quality in both.
Remember reading that it has been determined that it takes 5-7 shot in the vitals to guarantee 99+% kills. The 28 then will easily get it done, but an extra emphasis will be placed on good pointing/centering skills.
