I have asked this question before in previous posts but without much luck. There does not seem to be any standard when it comes to damage levels for various small arms, both in the official game and especially in mods.
I have downloaded submachineguns that deal out more damage with a single shot then an M-21. I would think that damage would be broken down by caliber.
9mm
.45ACP
7.62mm NATO
7.62mm Short
7.62mm Long
5.56mm NATO
5.45mm Soviet
.50 BMG
These are for the most part the most common calibers used in the game. If these had standard values most other calibers not listed about could at least be estimated.
What do others think??? hint hint