My shooting experience, being an M16 (I mostly fire it on semi), 240B (7.62 machine gun), SAW (5.56 machine gun), a buddies shotgun ( I don't remember the model but it was a pump), and his .30-06 (bolt-action), there was pretty minimal difference for me. The biggest differences between the weapons was rate of fire, recoil, and the sights. Otherwise I just used them like I would any other weapon and I did fine. So maybe I'm just good, but I really think its because all the weapons are pretty much shouldered the same. You stick the butt-stock in your shoulder, grab the pistol grip firmly, and assume a proper firing position.
So as to how to translate that, I don't really know. I don't think you properly can. But I do believe that the battle rifles are more akin to the snipers and shotguns. They are longer and most likely heavier than most of the assault rifles, plus I think most start out as semi-auto anyway. Since most of the hate seems to be directed at shotguns being weaker and battle rifles make the automatics group to strong, I think we should just move the battle rifles over to long arms. Also as a point, I think it makes sense to put machine pistols with other pistols, though since I never used them myself, I will defer to some else's greater experience. But since automatics are dominated by shouldered weapons, I don't think it makes since to have non-shouldered weapons included.