British .380 Centerfire Cartridge

[Curss]

Good evening gentlemen,

I have some questions concerning this mystifing cartridge

Old British revolvers and copies of the famous British Bulldog are often chambered in this .380 Centerfire... where can one find it? How close is it to the old .38 S&W in terms of dimensions and power?

I understand that the WWII .38/200 British cartridge is basically the same as .38 S&W with a 200 grain bullet but this .380 Centerfire is considerably older I believe. Any info would be appreciated!