During WW II S&W built revolvers for Great Britain. There are small variations that a collector would be interested in, but nearly all were basically the Military & Police model in .38-200 calibre, which is the British version of the .38 S&W, NOT .38 Special. After the war, most of them were sold surplus in the colonies. A two pound revolver for the short .38 S&W cartridge was not a fast seller, so many were "converted" to .38 Special by reaming the chambers for the longer cartridge.
Cogswell and Harrison is a fine old English gunmaker reduced by the post-war recession to taking in such minor jobs. 38 is .38 calibre, of course. I think the 1 15 is the new chamber length for Specials, 1.15". 4 tons is the proof pressure, in English long tons. That comes out to 8960 psi but the British procedure is equivalent to higher numbers in US practice.
Now what you have is a gun with a barrel for the .361" bullets of .38 S&W and chambers lengthened to take .38 Special (.358" bullet) ammunition. Worse, the .38 S&W although shorter than .38 Special, is larger in diameter. So the chambers are oversize at the rear and brass will expand to fit in an ugly bulge. At standard .38 Special pressures, it doesn't usually split. Not usually.
To double check, see if a .38 Special cartridge will go all the way in a chamber. If so, it has been converted as described. If not, then it is still .38 S&W and all C&H did was take off the lanyard loop and maybe reblue.
If it has been rechambered for .38 Special, put it down and walk away with your hand on your money. If it has not been converted, it would be a serviceable revolver considering the low power of .38 S&W and hopefully low price.
