Shooting a 7.62x51mm NATO 'Battle Rifle' on anything other that semi-auto is a waste of ammunition! That anyone would regard a semi-automatic only rifle as not a weapon of war is a bit of a wierd comment.
Our SLRs were semi-auto only, because the British doctrine was for aimed semi-auto fire; even now with SA80A2 (which is selective fire) the only time one tends to use automatic is either a) close quarters battle, or b) the lead scout in an ambush will empty his magazine to create temporary noise and fire superiority, whilst the remainder of the patrol counterattacks.
I've fired an FN FAL on automatic; the 1st and 2nd rounds tend to be on target, but the remainder are high. It's difficult to control.
In the Falklands we had 5 magazines per rifle and a 150-round bandolier; if you were shooting too rapidly someone would tell you to slow down, because we had to make the rounds count.