I dunno, my own testing attempt just had me feel anything past mid-range between the two squads is super RNG.
Depends on cover. Long range battles last for minutes, whereas open cover and close range fights are over in seconds. (I'm assuming you mean 'past' you mean 'further out'.) The thing is in long range fights with cover, squads drop to 2 or 3 entities pretty quickly, which slows the fight down. Without damage reduction from green cover (which volks can build!) volks face much worse RNG odds.
And though long range tends to favor Volks, there's a high degree of RNG in just about all infantry combat. There's always this sort of 10-20% chance of an upset I find. That's about as reliable as you get before vet and weapon upgrades.
Something needs to be done to control/deter USF blobbing. To make it more punishable or to make it not as rewarding. To make strategic play more viable. In this case, having the same weapon that is effective yes, not as effective on the move but as effective while static is a first step in my opinion.
Well, Riflemen's Garands have a moving accuracy multiplier of 0.6. Volks, Grens, Cons, Penals, all have a multiplier of 0.5. This isn't really too much of a problem because they only deal 8 damage, to Volks 12 and Grens 16.
BARs have a multiplier of 0.7. This is actually kind of middle of the road as far as weapons like Thompsons, PPsHs, and StGs are concerned. (I mean, LMGs have a moving accuracy multiplier of 0.75, so keep that in mind when using Obers.)
Rifles got to close the distance. They're designed to close.
Generally speaking I would classify
0-10 close
10-20 mid
20-35 far
The performance you describe is as expected especially in cover. Bolt action rifles are supposed to be better than semi auto (carbine) in far and heavy cover.
I think it's at range 16 that rifles garands and penals SVTs consider 'mid', whereas the volks Kar98k its 25. Most weapons don't achieve their 'close range' accuracy until there is 0 range. For the SVT its a range of 6 and for Garands its 3. It's minimal, but it affects the accuracy curve.
So it's in between 25 and 16 meters that Volks pretty much lose their advantage to Rifles. And at 10 meters the benefits of cover are mitigated, which quickly swings the balance of power towards the more rapid firing weapon.