The G3 has a rather decent accuracy, I have both been trained on it and later the Diemaco C8 (M4).
Hits very hard
and has good reliability.
Does not suite the future battlefield where engagement will be dynamic and from even shorter distances.
You would need a rifle that puts a descent amount of fire power, which the match grade 5.56x45mm ss109 (Mk 262) does and more importantly is suited for rapid and precise engagement under extreme conditions.
(Backside of the mk262 is the decrease in hard-target/barrier penetration.)