[Marek_Tucan]

Just working on something similar, OTOH...
Might be good idea to lower kill values (SMG = 5 has same HE kill as say 75mm gun, disregarding WH size).
As for ammo reserves, esp. for LMG they can be pretty large regardless of "official" values. It was SOP for squad members to carry additional ammo for MG, so I would rather take the "official" value of ca. 1000 RPG as a baseline, not as "full squad"
If I look at the detailed loadouts recorded in A-stan, it would seem that each squad member, regardless of his function, carries 200 rounds of 5.56 in the "Approach March Load", IOW not the Fighting Load, but at hand in the field, and Automatic Rifleman himself carries some 800rounds.
M240 gunner carries 300 rounds of 7.62. If it was used as a squad weapon, each soldier would carry ca. 100 rounds of 7.62 for him (I gather it was SOP in Vietnam if M60 was lugged around instead of auto M14). Asst. MG gunner lugs 400 and ammo bearer 300 (plus optionally M14, M136 or so).
Of course the practice varied, but it would seem that generally LMG gunner would carry some 20 kg load (weapon + ammo) and squad members each carry up to 3 kg of MG ammo. I can dig into my spreadsheets to see how much ammo would that represent, bt 7.62 NATO 100 rounds belt weighs some 3 kg and 200 rounds of 5.56 about the same. For actual combat carry most likely not all this weight would be carried, but some for sure as you do not want to go back to your packs in the middle of a firefight.
Also I think you should consider the squad size for rifle ammo allocations, as not every man in squd fires at once, so larger squads would tend to have more "shots".