Will new US ammunition prompt UK to change?

The M250 automatic rifle and M5 rifle are the latest guns to be introduced into the US Army, with the M5 becoming the standard infantry weapon.

With the new guns, comes new ammunition. 

They use hybrid steel and brass 6.8mm ammunition, which has 20 - 30 % more power and can defeat body armour from a distance.

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But will this change of guns by the US, with new ammunition, prompt its NATO allies – including the UK – to follow suit and switch to the 6.8mm ammunition?

James Reeves, an executive producer on TFBTV, The Firearms Blog, says he is unsure that there will be an "about-face" to follow the US.