Gurn: Those are British proof marks. What you have may be a .38 S&W British Service revolver (WWII made on the K frame, concurrent with the Victory model) that later has the chambers bored through to allow .38 special to be chambered...
Gurn never said
it will chamber a .38 Special cartridge.
OK, a little history lesson about these guns... a lot of this is rehashed from earlier in the thread, but I'll save people the trouble of searching back.
Great Britain received hundreds of thousands of S&W revolvers during WWII, both through the Lend-Lease program and outright purchase. All were chambered in .38 Smith & Wesson (.38S&W), which was called .38/200 by the Brits; it's an old low-powered round used in 19th-century S&W top-break revolvers. (The reasons for adopting such a wimpy round as a military service cartridge have been hotly debated ever since it first happened, but we'll leave that for another thread.
) Most of these guns originally had 5" barrels, dull black phosphate finish, and smooth walnut grips.
The British military converted to 9mm Luger semi-autos after the war and sold all of their S&W revolvers, mostly during the 50s and 60s, although a few trickled out later. Most went to the USA for commercial sale but some others went to European police agencies; many of these were subsequently resold again in the USA. During the 50s, there was a booming market in milsurp firearms through American mail order houses and neighborhood businesses such as gas stations and hardware stores, and most of these revolvers were sold through these outlets for dirt cheap prices. Most wound up in cash drawers and sock drawers in the bad parts of town. Some were sold relatively unmolested, but others were modified by the importers to increase their commercial appeal; typical modifications included reaming the cylinders out to accept more powerful and widely available .38 Special cartridges, refinishing, shortening the barrels, and replacing the grips with aftermarket ones. Depending on the importer, the quality of these modifications varies from pretty good to abysmal, but tends towards the latter.
These guns are generally considered undesirable by collectors.
.38S&W cartridges use a case that's shorter than a .38Spl, but actually use a slightly larger-diameter case and bullet, .361"-caliber rather than .357"-caliber. (Contrary to what you might assume, the .38Spl round, despite also being developed by Smith & Wesson, is based on the .38 Long Colt and not
the .38S&W.) If .38Spl cartridges are fired in one of these reamed-out .38S&W revolvers, the cases will usually bulge due to the excess chamber diameter; this can lead to hard extraction and split cases, especially if you handload and try to resize them. These guns usually also suffer from subpar accuracy due to the "oversize" barrel; however, they'll shoot better with lead bullets than harder jacketed bullets because the softer lead will expand and grip the rifling better. If you decide to shoot one, stick to standard-pressure non-jacketed rounds, and expect patterns rather than groups.