[Mobhack]

Every army (and navy) had different criteria to determine what was considered as "penetration". It could range from the tip just cracking the back of the plate through to 100% chance of it passing fully through. Some may require the projectile to both pass through and penetrate a certain thickness "witness plate" a certain distance behind the test plate as well (I.e. have some useful remaining energy post penetration).

So you need to know what particular test criteria was used for any given figures. Same goes for angle - some used 0 degrees as vertical, some used 0 as horizontal. Also, what was the target plate (RHA, Harvey steel, wrought iron etc). And was the penetration an average of several hits, or the best (or least) of several firings.

Loads and loads of variables. There is no one "true figure" for the penetration of anything really!.

We use the system SSI used for the original game, and that wont be changing.