It's all in the ADF (Ammunition Definition File) in the folder "systems"
F.e. this is the ammo for the german 280 mm gun (Graf Spee, Scharnhorst, etc)
; German 280mm AP shell (SKC34)
[AMMUNITION]
Category = Bullet
Type = ArmorPiercing
SubType = 280
Name = 280mm AP Shell
Radius = 0.280 ; Meters
Mass = 330 ; Kg
Speed = 677 ; MPS "average velocity" from muzzle 890
Range = 40000 ; Meters
DamagePoints = 8.5
ArmorPenetration = 18.0
The relevant point has been highlighte in red, but I'm unsure if this will cause the ammo to hit harder or simply to increased the % of damage. I guess it will be the last, since IIRC DC/SH2 had not implemented a simulation of the physic effects of objects colliding, just a "theoretical" count of teh damage points issued. Horsa will probably know better than me