9x23 Winchester is really a reloading proposition. I have one and I bought the equivalent of 1K rounds in loaded ammo and brass. Ammo is hard to find except via the internet. This ammo is not normally found in local gun shops. Winchester and Corbon make ammo. Starline makes brass that’s OK for reloading lower power practice rounds, but only use Winchester brass for full power ammo, it’s thicker. Full power load chamber pressures are in excess of 40,000 psi. One other thing, you will loose brass when firing the gun; spent brass is flung 10-15 feet away. It should be a great defensive round; 125 gr hollow point bullets @ 1450 ft/sec!
Well, if you’re going with handloads, there’s one that beats it.
9x25 dillon
Essentially a 10mm necked down to 9mm...or put another way, a 357sig stretch out to 10mm case length.