A nice piece in Defense Tech, that leads to the source article. In short, the Army’s approach to training and fighting was great for Iraq and an urban environment. In Afghanistan… not working so well. Long range fire fights are the norm you have to be able to fight at 500m.
The M4 with it’s short barrel is not suited to that.
The M16A1 or A2 from my time you could easily reach out to 500M, accurately with Iron Sights.
Go back further to the M14, and reaching out effectively beyond 500M is achievable with the 7.62×51 NATO round.
But adversaries are cyclical as we are seeing between the two conflicts. Our forces need to be able to operate effectively in both symmetric and asymmetrical environments. I think we are going to see these arguments occur on a regular basis. Every weapon system, and training approach is going to focus on doing something very well and by nature it will not do well on other areas.
An interesting read, go take a look Taking Back the Infantry Half-??Kilometer | Defense Tech.