Army1961
Member
Just purchased a S&W 1917 with the these marks on barrel. Any idea what they are, British proof marks maybe?
Foreign proof marks on 1917
- Thread starter Army1961
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7 Tons sounds like British proof mark. Can't read them all.
OP
Army1961
Member
Yes,it looks like the London Nitro Proof with an dexter arm holding a scimitar. In addition it has the crown over the letters GP on the right side of the frame. I will be able to get a better look when the gun arrives. Thanks very much for the info!
Looking a little closer I see .45 which is caliber. Then a case length, is it .900? and then 7 Tons which is pressure. That is how the British did things.
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The Tons /per sq in uses the English 'Long Ton' in their measurement system.
One Engl Long Ton is equiv to 2240 pounds
A conversion done from this site
Convert Long Ton (U.K.) Per Square Inch
to Pound Per Square Inch
(psi),
British And U.S. (Imperial System)
Says English 7 Long Tons/per sq in = 15,680 lbs/sq in
Sounds right to me for the 45acp (.900" case length cartridge)
The proof (marks) was needed to be done on the former Military revolver turned surplus before it could be released for commercial sale in England.
Very common to find these.
One Engl Long Ton is equiv to 2240 pounds
A conversion done from this site
Convert Long Ton (U.K.) Per Square Inch
to Pound Per Square Inch
(psi),
British And U.S. (Imperial System)
Says English 7 Long Tons/per sq in = 15,680 lbs/sq in
Sounds right to me for the 45acp (.900" case length cartridge)
The proof (marks) was needed to be done on the former Military revolver turned surplus before it could be released for commercial sale in England.
Very common to find these.
The British acquired 20,000 1917s during WWI from the USA.
Jim Watson
Member
Gough Thomas, English shotgun guru, compared US and GB shot shell loads and concluded that although British pressure ratings are in nominal long tons of 2240 lb/sq. in, the British proof ton is equivalent to about 2800 psi in US labs. I think due to the mechanical difference between the US radial pressure gauge and the British axial gauge.
