Originally Posted By: 2-piper
The "Old" 12 gauge standard for full choke was a 10% to 11% reduction in bore area for the choke. This gave a constriction of from .038" to .041".
This same % of reduction in the .410 would give constrictions of from .021" to .023".


I understand the percentage thing for different bores, but where was this "Old 12 gauge standard" devised, or originally decided/deduced? It's interesting, and I don't dispute it, but I've never seen it written before, that I can recall.

SRH


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