Have you verified that the bores are indeed .617"? I wouldn't have gone to the effort to measure the tubes and not measured the bores at the same time. Without that information the other measurements mean nothing. They may well be what the website says, but not necessarily so.

Mine is a wonderful little .410, but I wanted fixed chokes in it, and that's what I bought.

SRH


May God bless America and those who defend her.