Welcome to this forum.
This is the correct section to post it.
You have " .455 Mk II Hand Ejector - 2nd Model" British service revolver made under contract with S&W.
You didn't answer the question about a hole in the butt for a lanyard swivel, does it have a hole?
To be legal, it should have a serial # stamped on the butt of the grip frame to one side of the hole.
There are three basic categories of .455 (Webley) Mk II chambered Hand Ejector revolvers made by S&W under contract to the British for WW I. Yours is the 3rd category:
3. “.455 Mk II HE 2nd Model”
The 2nd Model continued in the .455 1st Model TL Brit serial range beginning #5462 to #74755, shipped 1915-17. The Canadian military also bought 14,500* .455 2nd Models. 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].
*Canadian military shipments of 14,500:
-1500 Shipped after Aug. 1915
-850 Shipped thru December 24th, 1915
-150 Shipped thru March 31st, 1916
-6,000 Shipped thru July 22nd, 1916 (at least 1 shipped July 29th, 1916
.455 Hand Ejector 45 Colt see post #10)
-6000 Shipped February 10, 1917