I’ve been told what brand of double is in 1923 before, but I cannot remember it now. I believe it was a British maker recently on the scene. Nothing the average fanatic has ever heard of. It may have been the same guy that made the rifle for the Bond film Skyfall.
The props department certainly got it wrong though, from the caliber to the coin finish, nothing is correct to the era. A 470, 500, 450/400, 465, 475, those would have been correct rimmed cartridges from the era. Nearly 100% of the guns would have been color case hardened, almost all of them worn to gray patina in just a couple years of use. A small handful would have been pewter color, having had their color case removed at the factory. None would have been coin finished.