Questions and suggestions on ammunition DR mod values for your damage mod.
Here I have plotted
20 average damage weapon using different ammo against popular armors.
Where did you come up with +35, -35, -20 numbers from? I understand you wanted to make JHP behave closer to vanilla version. However, by your own words, vanilla numbers "are pulled out of ass". I agree with it. So would it be better to optimize them against different type of armor to make them more distinct maybe? I don't think most user play with calculator in hands so for them see distinct difference would be a better cue.
In fact, you can just change the mechanics anyway you like to make them behave as you see fit.
One thing is that -20 and -35 DR mods are largely similar in effect. Maybe it would be worth spreading these values in general to achieve more noticeable effect? Like extend the scale from +100 for some exceptionally round and light projectiles like Buckshot Shell down to -50 for specially designed AP rounds?
Questions about specific ammo.
Rockets. They are not simple projectiles. Would it make sense to spread their DR mod values even more for more distinct effect?
Balls. Why 9mm
balls are more armor piercing than 9mm bullets? Any explanation or need for that?
Shotgun ammo. They are perceived by most people as not AP things. Even shotgun slug is worse than pistol bullet because it extremely thick and not pointy and not dense. Would it be more logical to shift them away from AP part of the spectrum. Like buckshot +80, regular +40, slug +0? This way buckshot can be used in early game for bigger impact against unarmored critters but obsoleted by lightest armor.