I discovered this mod a couple weeks ago and am having a blast with it, really digging the influences and how everything is blended into XCom. The scale of it is great and the amount of customization and content is the best use of the classic XCom software I've ever seen.
What's bugging me just a bit are the relative damage values with regards to the three main families of Earth-based automatic rifles that are available to players.
5.56 NATO family (L85, M16, Steyr AUG -- all 26 damage)
7.62 NATO family (FN FAL, Galil, M14 -- all 28 damage)
AK-derived family (AK47, Groza, AK74SU -- all 30 damage, a value shared with a variety of other high-end bullet-type rifles)
The 5.56 family I think has perfect stats; it is definitely a lighter-power round than any flavour of 7.62mm and so the 26 damage value is appropriate. The other two flavours of rifles should really have their damage values swapped, though: the 7.62x51mm NATO round fired by the FAL, M14 and 7.62 Galil ARM is a much more powerful round than the 7.62x39mm "short Russian" in the Groza and AK47/AKM series. The AKs should really have the middle value of 28 damage, and the powerful 7.62 NATO rifles should get the 30 damage.
It should be noted that the AK74SU doesn't even use the 7.62x39mm round; it is chambered for the 74-series 5.45x39mm round, which has comparable ballistic performance to the 5.56. The AK74SU should really have 26ish damage; certainly it's the gun least deserving of the big 30 damage value. If you want it to be consistent with the other rifles using AK mags, however, this could be easily tweaked to be called the AK-104: a shortened carbine version of the AK74 chambered in 7.62x39mm. This would allow it to be consistent in hitting power with the Groza and AK47/AKM, while maintaining the TU/accuracy characteristics of the shortened AK74SU.
Last but not least; the more powerful bolt-action rifles (such as the Mosin in 7.62x54mm "long russian" or the "Bolt-Action Rifle" that appears to be a German 8mm) should have their power tweaked up just a SMIDGE from 30 to 31 so as to reflect that these rifles are firing a bullet more powerful than the 7.62x39 or 7.62x51 used in the automatic rifles.
This is just a stack of tweak recommendations in the interest of better-reflecting the real-world performance of all these rifles that have been stacked up next to one another. If this doesn't fit with the equipment balance model employed in the game, fair enough, but I feel like so much effort is represented in the mod's content in terms of real-world hardware that it's worth being dialed in.
An example of a place where realism could conflict with balance: I would suggest the SKS be dropped from 30 to 28 damage since that's the damage value I've already recommended for its 7.62x39mm ammunition, but this might make it so weak it's not really useful at all. I hope to hear what perspective Solarius has on all this.