Pete;
I posted here on one ocasion some time back that a .410 was patterened in a 20" circle @ 25 yds & was promptly told I knew not whereof I spoke, that a 30" circle was proper, so didn't mention it this time. As you have found patterening in a 30" circle at 25 yds is useless for designating patterns. A 20" circle @ 25yds is proportionate to a 32" circle @ 40 yds, so gives a slight advantage to the .410. Especially prior to the introduction of shot cups etc, it needed all the advantage it could get, but to expect similar percentages in the same 30" circle 15yds closer in is simply out of the question. I suspect the 30" @ 25yds is special patterening for skeet guns, but this should be equally applicable to the "Gauges" as well as to the .410.
