I didn't bother to go back and read all the posts, and I've probably commented before this, but reading the thread title made this come to mind:
Whether or not we need a new combat rifle depends upon what war(s) we intend to fight next. We've been through this issue multiple times in the last century. .30cal rifles have been the standard for battle rifles because Europe, with it's large open areas, was the primary battlefront and .30cal was needed for the distances involved. The more popular weapons for jungle fighting in WWII were the lighter .30 carbine and the various 9mm and .45acp submachine guns, since they were effective over the generally shorter engagement distances in jungle operations and weren't as heavy or as unwieldy as a standard battle rifle (M-1 Garand or Enfield) and could provide a higher rate of fire (useful when your target is obscured by concealment). During the Korean War, those popular M-1 carbines were discovered to not provide enough knockdown power at the medium-to-far engagement ranges in Korea, although they met the need for increased rates-of-fire that proved necessary to defeat the human wave attacks used by our enemies in place of assault weapons. The M-14 was the first attempt to "standardize" around a common weapons system by mating a standard battle rifle cartridge platform with the ability to maintain higher rates of fire (20 rounds/mag vs 8 rounds/clip) while maintaining the reliability of the then-current battle rifle, the M-1 Garand.
Then came VietNam, with its jungle-fighting again, and the perceived need for full-automatic firing capability, and the M-1 seemed to be too unwieldy and too heavy again, so M-1 Carbines and M-3 Grease Guns and various other submachine guns began to make their way back into the inventory and eventually, the M16, a weapon developed as a survival weapon for the Strategic Air Command, was adopted as the new battle rifle. It worked fairly well in the short-ranged jungle environment again, but suffered from an inability to provide sure kills at ranges over about 500 meters, which lead our Recon Platoon Sergeant to attempt to trade the issue M-16s of our CAV recon platoon for the KATUSA guards' M-14s, when I was in Korea.
In Europe, the M-16's shorter range was offset by the fact that the AK had about the same range/accuracy, so infantry engagement, which tactics would revolve around anti-tank weaponry, was largely a wash in the battle rifle department.
Other engagements by the US in the latter half of the 20th Century again featured either relatively short engagement ranges (urban or jungle fighting) or where the battle rifle wasn't the primary weapon being used. It wasn't until we went into Afghanistan, IMO, that the increased engagement ranges involved in fighting from ridge-top to valley floor, or ridge-top to ridge-top again pointed up the deficiencies of the weapon system/cartridge being used.
By this point, the rifle has, for the most part, been modified sufficiently to make it reliable enough for military engagements, but the cartridge still doesn't seem to be able to make reliable kills at distances over 500 meters, making its users vulnerable to fire from full-sized battle rifle cartridges like the 7.62 x 54 often used by our adversaries.
If the military is going to attempt to remain wedded to one battle rifle system for all combat environments, it probably needs to continue to solicit designs that will increase the reliability of the system while allowing it to be modified sufficiently to meet both short-range and long-range engagement distances with a sufficient rate of fire to kill multiple attackers up close and sufficient precision and range to kill individuals at long engagement distances. I'm not sure any single weapon can do both of these.
Whether or not we need a new combat rifle depends upon what war(s) we intend to fight next. We've been through this issue multiple times in the last century. .30cal rifles have been the standard for battle rifles because Europe, with it's large open areas, was the primary battlefront and .30cal was needed for the distances involved. The more popular weapons for jungle fighting in WWII were the lighter .30 carbine and the various 9mm and .45acp submachine guns, since they were effective over the generally shorter engagement distances in jungle operations and weren't as heavy or as unwieldy as a standard battle rifle (M-1 Garand or Enfield) and could provide a higher rate of fire (useful when your target is obscured by concealment). During the Korean War, those popular M-1 carbines were discovered to not provide enough knockdown power at the medium-to-far engagement ranges in Korea, although they met the need for increased rates-of-fire that proved necessary to defeat the human wave attacks used by our enemies in place of assault weapons. The M-14 was the first attempt to "standardize" around a common weapons system by mating a standard battle rifle cartridge platform with the ability to maintain higher rates of fire (20 rounds/mag vs 8 rounds/clip) while maintaining the reliability of the then-current battle rifle, the M-1 Garand.
Then came VietNam, with its jungle-fighting again, and the perceived need for full-automatic firing capability, and the M-1 seemed to be too unwieldy and too heavy again, so M-1 Carbines and M-3 Grease Guns and various other submachine guns began to make their way back into the inventory and eventually, the M16, a weapon developed as a survival weapon for the Strategic Air Command, was adopted as the new battle rifle. It worked fairly well in the short-ranged jungle environment again, but suffered from an inability to provide sure kills at ranges over about 500 meters, which lead our Recon Platoon Sergeant to attempt to trade the issue M-16s of our CAV recon platoon for the KATUSA guards' M-14s, when I was in Korea.
In Europe, the M-16's shorter range was offset by the fact that the AK had about the same range/accuracy, so infantry engagement, which tactics would revolve around anti-tank weaponry, was largely a wash in the battle rifle department.
Other engagements by the US in the latter half of the 20th Century again featured either relatively short engagement ranges (urban or jungle fighting) or where the battle rifle wasn't the primary weapon being used. It wasn't until we went into Afghanistan, IMO, that the increased engagement ranges involved in fighting from ridge-top to valley floor, or ridge-top to ridge-top again pointed up the deficiencies of the weapon system/cartridge being used.
By this point, the rifle has, for the most part, been modified sufficiently to make it reliable enough for military engagements, but the cartridge still doesn't seem to be able to make reliable kills at distances over 500 meters, making its users vulnerable to fire from full-sized battle rifle cartridges like the 7.62 x 54 often used by our adversaries.
If the military is going to attempt to remain wedded to one battle rifle system for all combat environments, it probably needs to continue to solicit designs that will increase the reliability of the system while allowing it to be modified sufficiently to meet both short-range and long-range engagement distances with a sufficient rate of fire to kill multiple attackers up close and sufficient precision and range to kill individuals at long engagement distances. I'm not sure any single weapon can do both of these.