Well, that would explain why Duty guys are all well trained Russian soldiers with Russian gear, while Freedom is made of Ukranian with Western Weapons an they're also all drugged off their asses.
That's how its been for the whole trilogy. Duty are heavy armor and Russian guns, Freedom lighter armor with NATO guns.
Yeah it always surprises me how all the AK’s are the newer models. In general I think the majority of especially bandits and loners should have fairly old surplus weapons. Even everyone having MP5’s is a bit weird.
They seriously screwed up weapon balance and distribution in S2. Bandits and low-level Loners should be packing double-barrel shotguns, pistols, and some 9x18mm SMG's with a rare few having AKM's and Mosins, higher tier guys transition to AK-74 with some NATO weapons like SMG's and pump-actions starting to appear, with some older NATO rifles like old battered 'Nam era M16's and the AUG for the better guys in that ranking and Cold War battle rifles for some of the more experienced monster hunters, the weight and rate of fire obvious hindrances when it comes to artifact hunting or anti-human duties. Don't forget that despite the fancy looks the OG AUG was barely any newer than the AK-74 (entered service 197

, with all of the issues you'd expect a weapon its age to show. Top tier should be heavily dominated by expensive but ergonomic and light weight NATO guns (SCAR as well as the modern variants of older guns) with some guys sticking with the modern limited-production AK's that are reserved for use by Russian internal security, and with modern sharpshooter and battle rifles showing up more not just among the veteran hunters but those tasked with taking down other Stalkers.
Don't forget that older weapons can and should have degraded stats such as accuracy and even muzzle velocity, since nobody's shipping a mint condition 1960's era M14 to the Zone. Refurbished in some back-alley shop before final delivery at best, with parts sourced from God knows where. Same with weapons like the AKM. You're not getting factory-fresh weapons in the Zone, not unless you've got a trader who likes you and has connections. Thankfully technicians exist and they'll be
delighted to recondition your old, battered AKM you just bought or picked up off a dead body to factory condition, so long as you can pay them.
EDIT: One thing I'd like to mention and that most people are probably unaware of is that all those old battle rifles were built to old machining tolerances, and despite their barrel length and full-size cartridges were intended to be issued to every ordinary Tom, Dick, and Harry in the military as a basic service weapon. Their accuracy, even from the factory, was never intended to be anything more than "good enough" and would be considered absolutely horrendous by today's standards, with even the Germanically precise G3 needing to shoot roughly 4.13 MoA with special sighting ammunition to be considered fit for service.
https://en.wikipedia.org/wiki/Heckler_&_Koch_G3
Initial production G3 rifles differed substantially from more recent models; early rifles featured closed-type mechanical flip-up sights (with two apertures), a lightweight folding bipod, a stamped sheet steel handguard, a wooden buttstock (in fixed stock models) or a telescopic metal stock. Before delivery to the Bundeswehr, each G3 went through functional checks, zeroing the sight line (Anschießen) and a shooting test at the factory. In the process, five shots were fired at a target at 100 metres (109 yd) with particularly accurate sighting-in ammunition. The 5-shot group could not exceed 120 mm (4.7 in) (1.2 mil/4.13 MOA) diameter.
A modern M4 with basic ammunition is far, far more accurate than that.