A 14.5mm seems highly unlikely to me. It's too wimpy for this kind of helicopter. You would at least want to match the firepower of an IFV otherwise it's pointless as a gunship. The ZBD-04 has a 30mm autocannon. Their naval CIWS on the Type 052D are also 30mm.
That's a bit of a misunderstanding.
Naval and ground based auto cannons tend to be beefier then those used by attack choppers.
Of the dedicated attack choppers of the world, infact more often the use of the guns is not antiarmor like an IFV but soft vehicles and structures as well as making enemy infantry into pea soup.
Early model cobras used a combination 7.62x51mm minigun and 40x53mm grenade launcher in a turret.Mi24 and 35 differ based on variant but the stock model uses a 12.7x108mm gatling gun in a turret
The Russians today are offering a very light attacker with a fixed 12.7x108mm gun in the Kazan Ansat-2RC
, The Super Cobra, Mangusta, Rooivak, and indian LCH use 20mm guns those are the next step up from The 14.5mm.
AH64 series has the M230 but it's not the full power Bushmaster II which fires 30x173mm, the M230 fires 30x113mm a reduced power cartridge. This is also used in Eurocopter Tigers Gait 30M781
The Russians are about the only ones who for there attack choppers with there full power 30x165mm auto cannons on variants of the Mi24/35, Mi28, KA50/KA52.
The larger more powerful guns though demand heavier mounts the Russians often foregoing a turret.
The lighter calibers pack in more ammo for volume of fire and reduced recoil for better accuracy.
To put another way the weight of a M230 is about 120 pounds, a Bushmaster II is 344 pounds.
For aircraft everything is about weight for a helicopter balance is critical for control. So that weight savings is a big deal.
Generally for the Z10 I have always figured it was a 23x115mm.