I am corresponding with a person that has a SxS of unknown guage. First info says that the choke is a sloppy 12ga and a 12 and/or 16ga chamber guage will not fit inside the chambers. My take on this is that it's chambered for something smaller than 16ga and bored at least 12ga. Anyone have an idea on this?

Sounds like a "Vena distenda".

jack

First off what does "Sloppy 12ga choke" infer. Larger than 12ga bore or what?? Small end of a 16ga chamber gage should be at .732" or very close to 12ga bore (.729"). An 18ga bore is a nominal .637", don't have chamber dimensions, but adding an approx .070" would give .707" for small end. A Chamberless 18ga perhaps??? Maybe he is considering anything other than a "Full" choke as "Sloppy"

Nominal bore for a 14 gauge is .693" and for a 13 gauge, .710", but that's moot because it won't accept 12 or 16 chamber gauge.
He just needs to give better measurements and some gun details. One simple little thing would be for him to run a tight patch through the barrels and give you his opinion as to whether he feels any belling and/or constriction near the end of the barrels. Imperfect, but sans measurement tools, this might furnish a clue.

Yeah I know "sloppy 12ga" isn't exactly an accurate form of measurement. But I have asked him for better measurments in my first email. He hasn't replied as of yet. We'll see what's what. Thanks guys.

Have him take it to a knowledgeable gunsmith and get the chamber measured. It's not rocket science. Tell him to forget worrying about what the "sloppy" choke measures and find out for sure what the chamber measures. Who knows? the gauge might even be stamped on the underside of the barrel(s).

A machinist's scale, accurately read to the nearest 1/64" would be closer than some stationary bore gauges, and very inexpensive.