This is why I personally like where Fallout Tactics places the idea of pre-war technology although many might disagree on this. I just disregard any FO4 'design' concepts, to me, my head-cannon firmly places that the USA was using what we see now as current 'real' modern weapons there is no viable reason the technology of weapons design and manufacture should deviate too far into the Fallout timeline/universe. What's reasons behind this bulky designs and the uses of water cooling systems? hadn't this design outdated by 2077? or did the US Army has a different idea of multi purpose infantry weapons that could fulfill both the functions of service rifles and Squad Automatic Weapons ? the weapon designs are very WW1 to me.-side mounted magazine, and water cooled! and uses 5.56 mm ammo (and 30 round mag)! That's a crossbreeding between Browning M1917 and Benet-Mercie 'feedstrips' machineguns (Manufactured by the French, Italians, and Japanese arsenals) (or maybe Lewis too!). much bulky (and looks too unwieldy compared to its actual performances. Assault Rifle seen in Fallout 4 are much. Gene Stoner's design (NCR Service Rifle in Fallout New Vegas).
there are TWO different designs of Assault Rifles, both uses the same 5.56 mm ammo), or. all are 'Chinese' design), FN FAL (Fallout 3.
Instead of taking any usual forms of either Kalashinikov designs (F1, F2, and 3. is radically different to those of previous games.