Alongside being a popular self-defence round in the UK and US, the British Army adopted the Enfield No.2 series of break-open revolvers in the early 30s shooting a heavy bullet variant of the 38 S&W called .38/200 (from the 200gn bullet), and it was the standard British military sidearm for around 30 years. It replaced the similar design, but larger/heavier Webley MkVI and its .455 cartridge.
https://en.wikipedia.org/wiki/Enfield_No._2
The little 38 S&W round was no manstopper, but it was hoped the heavy soft lead bullet would make up for its deficiencies to some extent. Then when war looked likely in the late 30s, people got cold feet over whether there would be accusations that the round broke the Hague Convention rules on expanding bullets in war. So a 178gn FMJ jacketed bullet replaced the lead variety just before WW2. (In WW1, the Germans threatened to treat the 455 as an illegal round because of the lead bullet and were prepared to start shooting any captured officers carrying the revolver and its ammunition. IIRC, the Brits counter-threatened by saying they'd shoot a German officer PoW for every one of theirs executed.) In any event, it was taken seriously in 1938/39, hence the jacketed bullet version.
The 38 MKIIz 178gn FMJ cartridge was useless in any practical situation. It was notorious for failing to propel bullets right through the barrel and stacking bullets up in it until the cylinder locked up. (To be fair, much of that was probably post-war with old ammunition when revolvers and ammo were sold off as surplus.) I used to shoot with a fellow in the early 80s who was an infantry 2nd lieutenant in the 1960s and took part in the 'police action' in Aden against Arab insurgents who eventually forced the Brits out. This was like an early IS or whatever event with hyped-up and fundamentalist fighters attacking sole or small groups of soldiers.
https://en.wikipedia.org/wiki/Aden_Emergency
My friend was walking down a street with an NCO who was carrying a 7.62 L1A1 rifle (British Army version of the FN FAL) when they were charged out of nowhere by an insurgent running at them head-on, full pelt and swinging what my friend called a 'bloody great knife'. The NCO 'froze', and the lieutenant emptied his 38 S&W service revolver into the man's torso, the last shot when he was almost in touching distance. It didn't stop or even slow him and he nearly killed the officer who lost an ear. He was down on one knee having just dodged the first swipe and was helpless as the attacker swivelled and raised the knife for a second go. Luckily, the corporal 'unfroze' at this point and shot the Arab with his rifle at around 6ft range. ('That stopped him OK!' said my friend.)
Anyway, when he was discharged from hospital, his first act was to throw 'the bloody useless revolver' into the harbour as soon as it got dark ('lost in action') and replace it with a 9mm Browning 'Hi-Power', also carried a rifle whenever he could. He was told that afterwards that he'd got five good central hits on the guy, none of which exited. No doubt he'd have bled out soon afterwards from his wounds, but too late for my mate.
I bought a mint 1934 dated Enfield in original unissued condition still with the high foresight blade for the 200gn bullet installed sometime in the mid or late 80s. Reduced to £35 from £50 by my local gunshop as it wasn't getting any takers. A very nice little pistol and I got the reloading gear, but it wasn't exactly accurate due to the bullet issue. As
@S_Kyle says they take larger dia. bullets and none were available here then. Thousands were sold off in Britain after WW2 as surplus. mostly the less desirable D/A spur-less model, for as little as just a couple of pounds if dealers bought them in bulk. I'm pretty sure I saw a surplus wartime US made S&W revolver too in 38S&W. IIRC we bought thousands of what was normally a 38 Spcl revolver under the Lend-Lease arrangements as RSAF Enfield Lock couldn't make anything like enough of them in 1939/40. (Enfield Lock was later turned over to making nothing but 303 Bren LMGs for most of the war once new factories or suppliers were set up for its other smallarms.)
