A request for someone who has both a .40 cal pistol and a .410. Can you try a .40 bore lock in a .410 and let me know if it works?

Seems like it would be sloppy at best. .410 shotshells are interchangeable with .45 LC in guns like the Judge and Governor.

Neck diameter:

.45 LC - .480 in

.40 S&W - .423 in

.410 shot shell - .455 in

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Ego is the anesthesia that deadens the pain of stupidity

DISCLAIMER: These are the author's own personal views and do not represent the views of the author's employer.

Interesting. Never thought to look up diameters. That said neck diameters aren't bore diameters. So the bore diameter of .40 S&W is .401 and the bore diameter of a .410 is .41 I wonder if a 1/10th of an inch would render the bore lock un-usable.

What the hey is a "bore lock"?

If this is the one you're talking about, I don't think it will work. As you said, a .40 S&W is .401 but a .45 LC is .452

Yup those ^^^^