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Congrats, that's a rare find especially in that condition, seemingly all original, unmolested, and unconverted to an American cartridge! Your #12860 is a 4th version from the list below:
THERE ARE FOUR BASIC VERSIONS OF .455 chambered Hand Ejector revolvers made by S&W under contract to the British for WW I. All three groups include some triple locks, but those in the 4th group are actually 1st versions. “If” roll marked with the cal., those that are roll marked are only marked S&W 455 because all versions are actually reamed to also chamber the longer 455 MK I cartridge per the British contract. Therefore the ‘book’ references to caliber marking of 455 Mark II for all versions of S&W 455 chambered revolvers is a bit of a misnomer.
This is not be confused with the British revolver name “MK II” for the “455 Mark II HE – 2nd Model", which the British stamped “II” on the left rear frame of the revolvers and are known as such by them.
Note: The WWI British contract Colt revolver is marked ".455 ELEY", different than the S&W 455 marking.
The British markings vary greatly depending on the country of use, military units where they were used, and when/where they were imported, proofed, exported, etc.
There were several ways for these to make their way across the Big Pond to Britain, across the border to Canada, or originally sold here in the states and then immigrated somewhere else as evidenced by various assorted non - USA import, export, and/or proof stamps. Stamps also vary contingent upon how any particular revolver made the "trip(s)" and how long after WWI (stamping protocol changed over time).
THEY ARE:
1. “.44 HE - 1st Model”, ‘Triple Lock’, .455 chambering: 812* factory reconfigured unassembled or unsold ".44 Spl HE 1st Models", original chamberings unknown but most or all were likely originally .44 Spl. For the British military there are 666 #s 1104 thru 10417 (obviously not all serial #s in this range were used for the 666), the majority shipped Oct 21, 1914. The extra 146 in serial range #s 9858-10007 went to the commercial market; 123 to England Oct 1,1914, and 23 in the US Jan 1, 1918 [N&J pgs. 203-205]. These 812 .455 TLs were serial #’d in the .44 1st Model serial # range of 1104 to 10417. Per Neal & Jinks. Pg. 214, these are known to have been stamped SMITH & WESSON but not including the 455 cal. stamp.
* SCSW reports "over 800", but by shipped serial # count, it’s actually 812, 146 of which are commercial guns [S&W N&J pgs. 203 - 205].
The 666 were shipped in 33 different groups ranging from 4/8/124 to 4/28/16 with the majority delivered 10/21/14. These will often have added lanyard swivels when converted to 455 at the factory by drilling thru the serial # which is factory re-stamped on the left side of the grip frame under the stock.
The 146 .44 HE 1st Models that were converted/built as .455s assembled some time after the first 666 military .44 1st Model .455 TLs and sold commercially; 123 were sold to the British, shipped to Wilkinson Sword 10/1/14 and 23 sold in the US, shipped to Shapleigh Hardware in St. Louis, MO. on 1/1/1918.
The 23 at some point were converted to .45 Colt and it’s unknown if by the factory before shipment to Shapleigh or after delivery to Shapleigh. However even IF converted by the factory (as suggested in a September 2013 Rock Island gun auction narrative), the revolvers would not have a star on the butt or a rework date on the grip frame because they did not go back to the factory for conversion as rework, they were converted before they left the factory.
2. “.455 Mark II HE - 1st Model TL” in the new .455 British serial # range 1 to ~5800* assembled 1914-15. Thus creating 64** duplicate serial #s with the 666 1st version in #1. above in the “.44 HE 1st Model TL” .455 conversion serial number range.
*Previously reported as 1 to 5461. After this shipment there were some of this model sold commercially all in the 5502 - 5857 range, but including a few military issues in that range as well.
**There are 64 duplicates of TL #s of the existing 666 contract listed numbers of .44 HE 1st Model TLs factory converted to .455 (1st version above), #s 1104-5755 in the .44 HE # range (not all inclusive, known and listed [S&W 1857 – 1945 pgs. 204-205]), with 64 of the .455 HE 1st Model TLs (2nd version) #s 1 to 5800 in the Brit contract # range.
There can be ~ 4988 .44 TLs duplicated serial #s with .455 TLs.
There’s also duplicate #s of the .44 HE 1st Model TL .455s #5801 to #15375 (the last .44 HE 1st Model TL serial # known), of ~796 with .455 HE 2nd Models (3rd version) #s 5801 up thru #10007 in the Brit range, but the exact #s of duplicates is unknown because not all #s are known to have been used in either range.
3. “.455 Mark II HE - 2nd Model” (sans extractor barrel shroud and 3rd lock), and the cylinder ctr pin hole in the extractor star is reduced .020” with the associated Ext Rod rear tip reduced .020” in diameter from the TL versions, the ".44 HE 1st Model Triple Lock" factory converted to .455, and the ".455 HE 1st Model Triple Lock" produced in .455 (documented in Neal & Jinks Pg. 215-16.) This version was referred to as the MK II revolver by the British and stamped ‘II’ by them, upper left rear side of frame. The 2nd Model continued in the .455 1st Model TL Brit serial range and beginning ~#5801 (previously thought to be 5462) to #74755, shipped 1915-17.
By Feb 1916 724 were manufactured for the Canadians, chambered in 45 Colt, without a cartridge roll mark on barrel, presumed for the RCMP [H of S&W, 3rd ed., pg. 203].
Another 15 in 45 Colt were sold commercially in 1916; likely “over run” guns from the above order.
The Canadian military also bought 14,500 .455 2nd Models [H of S&W, pg. 203].
And 1105 2nd Models were released for commercial sales in the US, shipped Dec 1917 to Shapleigh Hardware in St. Louis [S&W, N&J pg. 216].
4. “.44 HE - 1st Model”, ‘Triple Lock’, same as #1. above, but not likely converted .44s, just assembled into .455s:
In April, 1916, [H of S&W pg. 203] S&W found enough [HE 1st Model TL frames, possibly already numbered as .44s, and .455 barrels and cyls] to build 691 .44 HE 1st Model [per Roy Jinks in various letters] Triple Lock frames [for chambering in .455* like #1. above].
*Although the last 691 TLs are likely numbered too high (12000 to 13000 and higher) and caliber stamped on the barrel, to be the version #1. above not cal stamped, they are the same . And not likely or possible to have a duplicate number in the .455 HE 1st Model TL Brit contract serial range #1 to ~#5800, but we don’t know much with certainty about these.
