Old Single Shot Chamber Question

[Schofield]

I just bought an old Iver Johnson 16 gauge single-shot shotgun and have no idea what the chamber length is. I plan on using 2 1/2 inch light loads, but would like to know if it is a 2 3/4 inch chamber just in case I needed to use one. I have read a lot of posts about having a gunsmith check it and I would do that if I had one nearby, but wouldn't it be a reliable test "if a fired 2 3/4 inch 16 gauge empty hull will seat in the chamber and lock-up without crimping the end back down any." Thanks

[oneounceload]

16's can be 2-1/2, 2-9/16, or 2-3/4...not a lot of difference, but enough

[badge851]

I just bought an old Iver Johnson 16 gauge single-shot shotgun and have no idea what the chamber length is. I plan on using 2 1/2 inch light loads, but would like to know if it is a 2 3/4 inch chamber just in case I needed to use one. I have read a lot of posts about having a gunsmith check it and I would do that if I had one nearby, but wouldn't it be a reliable test "if a fired 2 3/4 inch 16 gauge empty hull will seat in the chamber and lock-up without crimping the end back down any." ThanksThat would be one way to check it. An even better, more sure way, is to place an unfired/empty 2¾"hull in the chamber. If it ejects w/o any taper at the opening, it's a 2¾" chamber. FWIW, 1925 was the year 16ga guns (Itahaca®) were first made with a 2¾" chamber. I have a 1921 Ithaca® 16ga SxS. It originally came w/a 2 9/16" chamber which I had lengthened to 2/¾" many decades ago.

[zippy13]

That would be one way to check it. An even better, more sure way, is to place an unfired/empty 2¾"hull in the chamber. If it ejects w/o any taper at the opening, it's a 2¾" chamber.
The fallacy of this method has been discussed ad noisome in previous threads.

[PetahW]

[I just bought an old Iver Johnson 16 gauge single-shot shotgun and have no idea what the chamber length is.]
[ I would like to know if it is a 2 3/4 inch chamber just in case I needed to use one.]

Obtain a wood dowel that's will barely slide into the chamber.

Wrap the end with masking or electrician's tape (even with said end) until it's a snug sliding fit in the chamber at that end.

Slide the wrapped dowel into the chamber being measured, slowly & carefully, until it's forward motion is stopped by the chamber's forcing cone.
Do not force it as deep as you can, or you will distort the tape/shim, and thereby alter the measurement.

Mark the rear of the dowel at the rear of the barrel/chamber.

Withdraw the wrapped dowel, and measure the distance from the tip of the wrapped end to the mark - you should have the chamber length.

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