doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Chamber length...

Just dug a Lefever Arms Co. G grade, out of an old lady's closet. Said her husband left it there when he passed away.
Appears to be 12 ga.;chamber length unknown, but longer than 2 1/2".
32 inch barrels; NOT twist. Some kind of complicated damascus pattern.
Serial no. range, 214xx.
A fired Federal Gold Medal paper slides into the chamber, without curling the end over. 'Spose it's been reamed out....Unsafe at any speed? Brought it home, mainly to redo the barrels, as there seems to be a dearth of smiths willing, or able to restore damascus.
I'd like to shoot the old gun, but have no way of measuring barrel wall thickness. Buck Hamlin said he could measure the barrels for me.
But he's in Mo., and I'm in S.E MN.
Tire test fire with 3inch mags??? Or ease into it with RST low pressure???
Give me some ideas, please? Thanks, Grant.
P.S. Just kidding about the 3inch mags.....

Hope you are just kidding about sliding a Gold Metal into the chamber, and drawing any conclusions about the gun based on that.

Send it to Buck. Needs to be cleaned and inspected, and, inspite of what you may have seen here before, an old toothbrush and a rag are NOT the proper tools for that. You have pretty much outed yourself as not having the proper tools or technique do answer the questions you are asking. Good. Send it to someone who does, and take his advice.

Good luck.

Best,
Ted

A G grade Lefever in the 21xxx serial number range will most likely have Damascus barrels. I have never seen a G grade with twist barrels, but it is a Lefever so I will never say never. I would also expect 2 5/8" chambers, but if the gun was ordered for use as a heavy waterfowl gun, and the 32" barrels are a clue, then it is possible the customer specified longer chambers.

Your gun was likely built in 1893, so it could have had any manner of alterations in 126 years. I would try to find someone with the tools to properly measure 12 gauge bores and chamber. But remember, a fired shell is not a chamber gauge, and many times a fired 2 3/4" shell casing will slide fully into a shorter chamber without much resistance, especially if the forcing cones are not abrupt. This is also why the frequent suggestion to use a rolled up 3" x 5" index card is also not a great choice. And even those fancy tapered brass chamber gauges may go in further than true chamber length if the chamber is a tiny bit oversize in diameter. I agree with Miller on the simple use of an inexpensive 6" stainless steel machinists scale or ruler. They aren't very expensive. I probably have 10 or 12 of them, and found most at flea markets or swap meets for $1.00 or less. They have graduations in 32's and 64's of an inch, so are more than precise enough. You simply set the barrels in a stable position pointing toward a light or sunny window and look into the chamber. You should easily see the transition between end of chamber and start of forcing cone. Slide the scale into the chamber until the end reaches this transition and read the length at the breech end. Many of these scales have a sliding pocket clip that can act as a stop to more easily get a reading without disturbing the position as you raise your head. Double check your reading and check both chambers, and you're good to go... as far as knowing the chamber length.

As far as having been reamed out and unsafe at any speed, only someone with proper wall thickness measuring tools can know for sure. But in my experience, odds are everything is original unless there are obvious signs of reaming and honing. Most of these guns, especially 32" models, had pretty heavy wall thickness to start with, so even if the chambers were opened up to 2 3/4", it probably wouldn't make the gun dangerous. But starting off by shooting a 126 year old Damascus double by firing 3" mags is only more likely to damage the old wood than to blow the barrels. You obviously know better than that. Get it checked by a competent smith with the proper tools, and enjoy it with appropriate loads. Or sell it to someone who will.

Use the 6" machinists scale to determine chamber length. The procedure has been detailed on here many times, and is accurate.

SRH

A few comments here. In early days of US shotguns "Standard" chamber lengths were 20& 28 gauges 2�", 16 gauge 2 9/16", 12 gauge 2 5/8" & 10 gauge 2 5/8". Other lengths were available on order in some cases up to 3�" length. Very soon 2 3/4" also became a standard chambering in 12 gauge & 2 7/8" in 10 gauge.

I have a 12 gauge G grade Lefever SN 20,633 which is a two hook Damascus gun which has 2 5/8" chambers. I also have a large single hook G grade Damascus SN 29,471 which has 2 3/4" chambers. An E grade 10 gauge Damascus of mine is a rod cocker with side pivot top lever SN 10,515 has 3" chambers.

My personal with older guns is one is much more apt to run into chambers a few thousandths undersize than oversize. Current SAAMI specs suggest a minimum chamber diameter at the junction with the cone of 0.798"
What effect does this have? "IF" the chamber is even .003" over the gage diameter & you have one of the newer 1�" long forcing cones the gage will go in approximately 1/16" deep.

Chambers will normally have as a maximum a taper of .005" per inch. A gage even .001" larger than the end of the chamber will thus stop a whopping .200" short, showing a chamber more than 3/16" short. A chamber 2 or three thousandths undersize does NOT create a dangerous situation. I have little doubt that many shooters have been sold a re-chambering job when it was actually to length, to begin with, but a bit undersized.

I do not have a current modern chamber length gage to measure. "IOF" someone does & also has a micrometer I would like to have an actual measurement of the Working portion's diameter. I highly suspect it will be right on that 0.798" SAAMI Minimum. This is why working with older guns I find the 6" scale to actually in many cases the more accurate method.

Will also comment we use the term Machinists scale, and yes I do too Stan.
The scale doesn't have to be Machinist quality as in a Starrett or Browne & Sharpe Etc, a General from your local Home Improvement store will do the job quite well. We're not trying to measure down in Thousandths of an inch here.