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2 1/2 or 2 3/4 ?

910 views 7 replies 6 participants last post by  burch 
#1 ·
The double I have is the one made in St Etienne France. I`m trying to figure out what size the chambers are. A 2 3/4 shell will fit but was told that with a 100 year old gun it may be 2 1/2. The markings on it have two numbers 18.2 and 6.5. The 18.2 I believe is 12Ga. Can anyone tell me what size the chambers are ?

Burch
 
#2 ·
I had the same issue with my St Etienne 16 ga and ended up go to my gun dealer and had them measure them. A good gun shop should have a chamber measuring tool. Mine are 2 1/2". You can't tell by putting a shell in there. The length is the post firing length and even if you put a fired shell in there, the crimp area may not be straight enough to tell.
 
#4 ·
It needs to me measured with a chamber gauge. I just picked up a 2 1/2" gun and shot it today with 2 1/2" shells from polywad. They are 7/8oz loaded with PB, so pressures are low. I would suggest having someone familiar with old doubles take a look at the gun, measure the chambers and advise you prior to shooting it. If it's a sound gun there should be no problem with shooting it with the proper shells. Do some homework.
 
#5 ·
burch

The 6.5 figure is the chamber length in centimeters; equivalent to 2 1/2". !8.2 is indeed the bore size, equivalent to 12 gauge.

The "PT" mark you mentioned in another post is a Proof mark indicating "Poudre T" (Powder T) denoting a Proof pressure of 960 kg/cm² if the mark is surmounted by one crown and 1370 kg/cm² if surmounted by two crowns.

All this means is that when the gun was subjected to Proof it could safely fire a 2 1/2" 12 bore cartridge; it means very little now.

Given these relatively modern Proof marks, I doubt you gun is anything like 100 years old. Nevertheless it should be examined by a competent gunsmith, not your local store "expert". Only a fully trained man can give a valid opinion as to the current condition.

If the bores and chambers are free from pitting, haven't been honed or elongated, the ribs are showing no signs of being buggered about, the gun isn't "off the face", the underbites are tight, and there are no cracks in the action or standing breech, your gun is as safe today as when it was made.... but only an expert can tell you. 2 1/2" shells are freely available in the US.

Regards
eug
 
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