doublegunshop.com - home Forums General Discussion DIY Gunsmithing @ doublegunshop.com Measuring chambers

I recently bought an 1885 10 bore from a seller who told me that it has 3" chambers according to his chamber gauge. I don't have a gauge, but an unfired 3.5" 10 bore brass shell leaves 1/4" protruding from the breech, suggesting that the chambers may in fact be 3.25". This test worked when I tried it on a 2.5" 12 bore: a 2.75" brass shell only goes in 2.5".

Is this a valid test of chamber length?

Doubtful. Just measure it. Roll a piece of paper and insert. Mark the place it stops and use ruler to see how deep the chamber is...Geo

No. It is not.

I like and use the machinist's scale method. Very repeatable with a little practice. George's method works too.

SRH

Thanks for the quick responses.

I have tried both those methods and can't get consistent results. I clearly don't know what I am doing but will try again.

Why don't you buy a chamber gauge for $45...never be in the dark again...


https://connecticutshotgun.co/handy-model-chamber-length-and-choke-gauge/

Then I would need to buy more guns to justify it and I can't afford them!

Yeah? What are your eyes and/or fingers worth?

How about this? I have the chamber gauge set I pictured above, the 10 gauge brass is 0.82" or 21.2mm wide. Make yourself one out of some old metal sheet and see how far in it goes.

LGF,
I think it is doubtful that your chamber is 3", I think the standard, at the time, was 2 7/8" or shorter. If it is 2 7/8", it would be pretty easy to mis-measure and think it is 3".I think Buffalo Arms( no connection) may have shells loaded for old guns.
Mike

No need to buy a chamber gauge for $45. Two doublegun friends here in town just come over to my house whenever they buy a new gun and use my Galazan gauge. Find a friend locally who has one and you can usually pick up a free beer and political advice in addition to getting the accurate measurement...Geo

I can see where owning a good gauge could become expensive...

If there is a good idea of what type of shells should be used, does a chamber gauge help much in this situation.

By the way, the $450.00 bore gauge in the Galazan ad is a wonderful alternative to the $125.00 Skeet's type gauge. It measures 28 to 10 gauge, which the Skeet's gauge will not do. Although admittedly more expensive than Tony's $45.00 chamber gauge, it will measure chambers as well as bores.

Plugs are fine but can be misleading , some older chambers may be a little tighter than modern ones so a modern plug will no go in fully . I have had this on numerous 12 bores when the plug would not go all the way to the bottom of the chamber , but a couple of turns of a new chamber reamer cleaned them out with out deepening . Eye and a steel rule should give you a fairly close reading depending on the cones. Guns of this period made for roll turnover cases often had much shorter cones .

Thanks for all the good advice, gentlemen. A bore gauge showed that the chambers are indeed 3".

A wall thickness gauge gives a very accurate measurement of chamber length. Just slide it in and as you get near the front of the chamber go slow and watch the dial. An abrupt change will be where the forcing cone begins.