Would still like to hear from somebody who's measured the muzzle diameter.
Why? The muzzle of my CZ 550, which I've owned since 2002, measures .605", which is considered by some as pretty skinny for a medium-bore barrel 23.6" (60cm) long. Yet it has always shot REALLY well, whether in the original clubby factory stock or the much slimmer Serengeti Rifles custom stock made five years later. Believe I have yet to try a handload that didn't shoot inside an inch for three shots at 100 yards, with many doing much better. Which, in my experience with a number of 9.3x62s, is basically how they shoot--which is of course is far better accuracy than needed for just about any use imaginable for the cartridge
I just looked at some 9.3x62 load data and the cartridge uses many of the same powders as the easy to get along with 308 Winchester. I suspect a bullet weight / bore size /case capacity mix that thrives on "Varget class" powders contributes to the friendly nature of whichever cartridge lands there.
