OK, I know it's hard, but imagine a world where NATO was like Yugoslavia and actually made a meaningful attempt to adopt the best possible rifle for its infantry across all of its nations based purely on its performance (I know from Bojan that the Yugo trials also featured feasibility of production with nationally extant resources etc. so we are going a step further and going totally in individual merit here). .280 British has been adopted as the NATO standard calibre and a rifle has to be selected. All are to be optionally equipped with the same unity power optical sight (specific eye relief variants allowed) as an alternative to irons, so sights alone can't be a significant factor.The following are trialled in this calibre (please assume that they work as well as in 7.62x51 NATO or CETME).
Armalite AR10 (fluted steel barrel version)
Which wins, and why?
Late edit: the designs can be scaled to the cartridge - not just re-barreled etc.