As I've said before, sitting in a tree stand with a heavy rifle and 5 rounds of ammunition waiting for a deer to walk by has nothing to do with warfare. Period. Anyone who thinks it does has never been in a position where they carried a rifle daily for the purpose of taking human lives.
As for this gem:
the xm8 carbine and hk416 both perform better, and id like to see them rechambered for a bigger round, maybe 6.5 grendel or 6.8 remington
The XM8 was discontinued because it
melted during sustained fire trials. Seriously. Look it up.
The HK416 offers zero real-world performance advantage on unsuppressed weapons with 14.5"+ barrels. It does, however, offer increased price and make for a more nose-heavy (read: slower to maneuver in CQB) rifle. In suppressed applications and extremely short barreled weapons, it has an advantage, but then the go-fast types using shorties and suppressors have access to whatever weapons they need anyway, so general issue of the 416 would just be a massive waste of funding that could be better used on things that actually do need replacing.
A short, fat round like the Grendel will never be used in a military automatic weapon because of feed reliability issues with that case design.
Since the 77gr Mk. 262 round provides virtually identical terminal performance to 6.8SPC out of 14.5" and up barrels, systemwide conversion would again be rather pointless, and again the go-fast types with a need can get the 6.8 when they need it already.
If you have no experience killing people with the M4/5.56mm combo on a regular basis, and get your information from the internet, HK's marketing department, and deer hunting, you have no business trying to tell the military what weapons they need to issue to front-line troops. Period.