See the Yanks are starting to introduce a new rifle for close quarters with a 0.68 round. Saw it on the future weapons programme and it stops everything in it's path. There has long been speculation re.the 0.556 having not much kinetic energy and it seems a person once shot by the M16 turned around and looked at the chap who shot him not knowing he had been shot! Another armourer once told me the tumbling bullet was made out to be more than it was,you need a round that will knock someone down. I don't know why we went for the 0.556,top long range accuracy is not paramount any more,close quarters seems the mode of most engagements nowadays and you need to put a man down not drill a hole through him. Just my take and probably wrong in a lot but seems the Yanks have decided to have more stopping power,will we follow?I doubt it. Who has the advantage if an AK47 tears your arm off with a round and a SA80 drills a hole thru you? Guess I need a combat expert to put some slant on this as apart from being an ex-armourer,I have no experience on combat.