I'm your huckleberry. I will take the 6.5 Creedmoor over the .308 and jump on the bandwagon. However, I wonder if we are suffering from a case of Afghanistanitis and we just want to fight the last war again. I predict the next conflict will return to typical engagements under 300M and we will be clamoring for lower weight and higher volume of fire.
I don't think carbines go away by any stretch. I also don't think that .308 goes away either since it will load more reliably in semi-autos than 6.5 C, which is a concern for MGs and if using as a battle rifle rather than a DMR role... The greater weight, etc, isn't an issue for MGs that are typically either vehicle mounted or stationary defensive.
For longer range use, I like 6.5 Creedmoor and .300 win mag, each serving different roles. Their ballistic similarity is great for interchangeability too for precision/marksmen to be able to select a weapon for the mission and have to do less cross training to effectively deploy each.
But when you consider the weight, ballistic advantage, higher sectional density of 6.5 C vs .308 (meaning greater penetration), etc, it's pretty difficult to say that it's not the way to go. The same "it's great b/c it's a flat shooter" for 5.56 N vs 6.5 C applies here, but with much less loss of efficacy at longer ranges due to 6.5 C's high ballistic coefficient resulting in greater energy than .308 at range...
I just don't see many instances where you wouldn't want to at least have a few marksmen/precision folks in every platoon, if not one per squad. You could also certainly also equip each with a breaching shotgun too with some additional ammo for indoor room clearing -- indoors is about the only environment where they'd be at a significant disadvantage vs the M4, but even then for urban combat, you would likely have your precision/marksmen equipped w/ an 16-20" SPR/DMR rig in 5.56 rather than a longer range weapon in 6.5 C... And in urban combat, you'd leave the precision shooting to proper sniper teams in overwatch positions and keep the DMs w/ their unit.
Now the SPR was originally 16" as designed, but became a comprise weapon design at 18" due to Navy Special Warfare wanting 16" and Big Green wanting 20" barrels. All things considered w/ 6.5 C in the mix, I'd return the SPR to the original 16" configuration (especially w/ suppressors now being more broadly issued), and issue the 6.5 C in 18-22" configuration when longer range is needed...
Insofar as future wars -- we're either looking at warfare in major urban centers like what Israel sees--and they went to bullpup 5.56s for that use -- or longer range extended engagements with near-peers where mobility and lack of troop concentrations are critical to survival (like was the plan for direct combat w/ Soviets during Cold War where tactical nukes, etc, were a concern -- however now, it's technology like mini-drones, other eyes in sky, flir/heat imaging, precision strikes, etc, that become the concern). Yes, Afghanistan is unique terrain; however, its extremely varied environments with engagements at unknown ranges, etc, would most likely be the case in combat against most irregular forces -- and in that case, the 6.5 C would again be of benefit, as w/o more capable longer range weapons, the lack of that capability would be exploited by the enemy.
The thing I come back to w/ 6.5 C is that it's a little more rifle than .243 winchester insofar as bullet and recoil, but has capabilities that exceed the .308, and even .270 win at range. The fact that there's so little compromise is what makes it something!
