1 - A .30 cal battle rifle will NEVER be adopted as the issued arm for the US military again, it just won't happen. A few in some units will be issued M-14's and AR-10's or some thing in 308 but the idea that anything in .30 caliber will replace the M-16 is a nonstarter.
Probably correct so long as we have ± 15% female troops. At least for as long as conventional cartridge weapons remain the state-of-the-art; there are some liquid-fueled cartridge prototypes that are getting close to the requirements for practical use, but there are still a couple of materials breakthroughs needed.
2 - The logistics folks have spoken and apparently killed the 6.8SPC, I don't know how serious the Army or other branches were about a new round but it seems it didn't matter.
Yep. Though it seems that SOCOM, at least, is going to get a new .40 S&W caliber [no doubt with a NATO metric designation that'll take around 24 months for full approval] handgun to replace the M9 Beretta...probably a Glock 23 or thereabouts.
3 - The 6.5 Grendel has virtually no taper and I don't think was ever a serious contender because of that, Great ballistics though.
Interesting and reasonably effective with a 15-inch M4 carbine. But both the Army and Navy played with .243/6mm and 6.5 variants of the 5,56mm cartridge when the JSSAP tests of the M16A2 were going on around 1979-80. And the Grendel is less well-suited to belt-fed use with the Squad Auto Weapons, though barrel changes take all of about five seconds. One thing that might bring about at least limited use of the 6,8mm cartrridge though: If the Russians start rebarreling AK103s and AK74s [and RPK74s] for a .270-.276 diameter bullet loaded 5,45x39.5 round.
4 - The wounding and killing characteristics of the 5.56 under 100 yards apparently is not the problem, this is with 55, 62 or 77 gr. bullets. The majority of complaints apparently only concerns shots over 100 yds. out of weapons that usually have shorter barrels. The lower velocity has the bullets falling below the velocity that allows the round to fragment prior to hitting enemy combatants therefore the pencil hole wound rather than the tumbling, fragmenting wound that puts people down and out of the fight.
Effectiveness against folks with body armor is another particular concern. So is cold-weather performance. Ever notice how we're always so experienced and well-prepared to fight the last war, but never the next one? And if we ever go up against light armoured vehicles, or effectively hardened *technicals* as in Somalia again....
5 - The majority of ammo in 7.62x39 currently on the battlefield has you shooting howitzer trajectories beyond 100 yds.
It gives a heck of a beaten zone with the 24-inch barrel of the RPK though. Considering that the 7,62x39mm M43 [as in M1943]cartridge was developed to replace bolt-action rifles that shot a cartridge adopted in 1891 [and that's STILL used in SVD sniper's rifles and PK machineguns] and pistol-caliber PPSh and PPS burp guns, the old AK loading has earned its keep. And some very qualified users who have their choice of older AKMs or newer 5,45mm AK74s pick the one that pushes the big heavy bullet every chance they get.
If we can agree that some of the above is true perhaps not ideal be true, maybe a reasonable debate can ensue. Finally, not trying to thread hijack, but what, (I know the logistics folks would have a fit with this idea also but) would the learned gun folks on FR think about retiring the current M24 and M40's in 038 and replacing them with new rifles chambered in 300 WSM. The Army is still using the M24 a long action in 308 with the pretense that can rebarrel to .300 Win Mag, well I counter if you were ever going to up to the Win Mag, Afghanistan and long desert shots in Iraq would have been the time. The Marine Corps uses the M40 and short action, but if you can get a few hundred fps over the 308 out of the same size rifle I'd think it would be the way to go. What say you all?
The Navy looked real, REAL hard at the .300 Win cartridge, long a Navy Palma Match Team favourite, during the development of the Navy M86 sniper's rifle, hopefully swiping the best from the Army M24 and the Marine M40A1/A2. And stuck with the 7,62 NATO chambering, in part for commonality with the platoon LMG [and the Navy is tinkering REAL hard with a 7.62 SAW, the Mark 48, mod 0] If more than a 7.62 is needed, it probably ought to be a .338 Lapua....and probably on the L115A1 AWM rifle platform, as per the Royal Marines issue.
Opps, I reread what you wrote about the adoption of the 7.62x39 and yes you're correct about the timing and such. The bigger bullet hitting harder is kind of the point of the thread and the x39 does do the job. When in doubt read it again I ought to slow down on the quick post reflex.