Sadly the 5.56mm change brought into UKicon Forces, was so that we could allign with the United Statesicon after the Vietnam War.
IMHO the one biggest military mistake we have made since WW2.
We should have stood our ground, and told others to conform to our more effective 7.62mm round.
Due primarily to this change in my view, we now see a proliferary of several weapons in UK sub units such as a Platoon size, all carrying a variety of rounds.............ludicrous and one where it will see soldiers travelling a dangerous path in major conflicts of the future!
I am sure there are those who have greater experience in this "misjudgement" over the years and seen it first hand.