J. R. WEEMS
Member
Any one know of a maker of .360 200gn bullets?? I know of a tin, unopened case but have stayed away from them because I expect they are corrosive primed. I havent had much luck looking around yet.?? THANKS! 
If you are looking to duplicate the "correct" bullet weight for the British .38-200 as loaded by the brits, then that is a 160 gr RN. The military bullets were, of course, jacketed.
The British actually adopted the .38 S&W as loaded with a 200 grain bullet, the "Super Police" loading, hence the cartridge designation of .38-200. However as stated above the issued ammunition was loaded with 160 grain bullets not 200 gr.
The WWII and post-WWII British service round was the .380 Mark 2. It used a 178 grain FMJ bullet (NOT 160 grain). The pre-WWII service round was the .380 Mark 1, with a 200 grain lead bullet.
“Grain” is the same across all systems. One grain avoirdupois equals one grain metric equals one grain apothecary equals one grain troy.