Well, it’s the difference in whether you’re using groove or bore diameter to measure!
The British used bore diameter, and used .303”, and grooves are .312-.314”.
Likewise the 7.62x54 Mosin Nagant.
The .30/06 and .308 are .299-.300” bore (hence .30cal) but are .308” groove diameter!
Confused yet! (Some early.30/30’s are .307”!)
The .32acp is .309” +.002 or -.001”. But it’s a .32!!!
The .32 Colt was a heel type bullet (like .22rf) and was .33”, but the .32 S&W was .313”, as is the .32 S&W Long.
The .327Federal Magnum is .312”!
So, YOU should have been CORRECT! It should be .32 Super!
But, S&W chose to call it a .30 Super Carry....
We’ll give you a “C” , and a (deleted!). for “participation”......
(I’d rather sit in the corner with a dunce cap, myself! And mutter, that’s what I get for opening MY mouth!)