I suggested something like this for Adamant a while back (well, I suggested standard armor and then light and heavy armor mounts) but Fyron said it would be too complicated; he only wanted 2 types of armor
Just a silly question... why are you measuring the gun bores in millimeters but the armor in inches?
edit: oh, and maybe it would be good to have a "default" thickness for armor - in other words, instead of your scheme where the armors have 3 HP unmounted and the mounts raise their hitpoints by factors of 10-32, have the armors 30 HP unmounted and have the mounts raise their hitpoints by factors of 1 (no raise) to 3.2. That way if you forget to use a mount on your armor you're not screwed, you just get a "default" 1-inch armor
