One of my .410s has a .034" full choke, which is the most constriction I have ever measured on one. Yours, as measured, would be .050", which is overly tight for an original 12, let alone a .410. The little suckers can be difficult to measure at times. I'd check the readings again, too. I'm not saying you're wrong, but it's far enough out of the norm for full that it warrants a re-measure, at the least.

SRH

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