they just adopted a new 5.56 loading (SOST, which is picking up issuance numbers more and more) that probably took a decade to finally swing into production.
We'll be lucky to see a platform change within the next 20-30 years, at the rate things are going. They will have to make something that would be logistically superior and/or at least offer better general performance than our current guns. This means that until the next great leap forward comes along, we're stuck with the M-4/16s, for better or worse.
also, diameter has little to do ballistics. The weight of the projectile versus speed/velocity decides most of that.
We'll be lucky to see a platform change within the next 20-30 years, at the rate things are going. They will have to make something that would be logistically superior and/or at least offer better general performance than our current guns. This means that until the next great leap forward comes along, we're stuck with the M-4/16s, for better or worse.
also, diameter has little to do ballistics. The weight of the projectile versus speed/velocity decides most of that.