Winds of Change has an important post on the subject of something very basic: having a rifle and a doctrine that can engage the enemy at the range where he is usually encountered. In Afghanistan, that's out to about six hundred meters.
While the infantryman is ideally suited for combat in Afghanistan, his current weapons, doctrine, and marksmanship training do not provide a precise, lethal fire capability to 500 meters and are therefore inappropriate.
Comments from returning non-commissioned officers and officers reveal that about fifty percent of engagements occur past 300 meters. The enemy tactics are to engage United States forces from high ground with medium and heavy weapons, often including mortars, knowing that we are restricted by our equipment limitations and the inability of our overburdened soldiers to maneuver at elevations exceeding 6000 feet. Current equipment, training, and doctrine are optimized for engagements under 300 meters and on level terrain.
The "easy" solution is to buy a bunch of Grendel kits for the M4, and ramp up production of the round so that we can have it in the industrial quantities we need. By "easy," I mean, "not even a little bit easy, but still easier than the alternatives." Nevertheless, Doc Russia -- a former Marine rifleman, who is now a medical doctor -- has often endorsed the Grendel round to me, and I'm prepared to believe that he is uniquely positioned to understand the issues involved.