Nobody, anywhere, calls 9x18 Makarov the “9.3x18”. Yes, it’s a slightly different diameter than the .355x17.3 (oops, I mean the 380 auto). And if we are being prigs over diameter, the 38 Special is .357 in diameter, not 38.
” 38 Special is .357 in diameter, not 38.”
The old Navy Colt .36 fired a .38 ball.