US Military Dumps 5.56 NATO!

Last updated March 2026 · By Nick Hall, firearm news writer covering US military small-arms procurement transitions

The US military will abandon the 5.56 NATO cartridge and switch to a more powerful, longer range 6.8mm round instead, according to reports. It would be a heinously expensive move to ditch the foot soldier’s round of choice and we’re not entirely sure it’s going to be a complete stepchange. Even if it is, it will be phased in over years.. This is the end of a love affair that has lasted more than 50 years. FN invented the 5.56x45mm NATO cartridge all the way back in 1961. By 1963, the US military was starting to use this utilitarian, cheap and reliable round.  The new bullet should combine the strengths of the 5.56 NATO, the 7.62x39mm and possibly even the 6.5 Creedmoor. If the US military can produce a round somewhere in the sweet spot of those three rounds then the whole firearms industry will change overnight. If… There do still seem to be some variables here and I’m not totally sold. The military doesn’t normally make rash choices like entirely new rounds, there is enough proven technology out there and this might just have been taken out of context.

Colt M4 Replacement – Revolution Not Evolution

Still, some sources say the Next Generation Squad Weapons will come with a 6.8mm and the government has invited tender bids from arms manufacturers for the Colt M4 replacement and the spiritual successor to the M249. We just published a list of the world’s best assault rifles and the 5.56 NATO basically dominates the top 10. The simple truth is that the rest of the world will follow America’s lead when it comes to guns and ammunition. That’s not arrogance, it’s a simple case of free market economics.

New US Army Rifle Due in 2021

This change won’t actually take effect for a while, though, and that’s a good thing. This is a serious stepchange for the gun manufacturers, gunbroker, just about everybody. A lengthy, 27-month development period is built in to the schedule and there is no way these guns will land in US military hands until 2021. So, don’t stress, you have plenty of time to enjoy your 5.56 NATO. Just know that this era is coming to an end and the next generation AR-15 will come with a 6.8mm thumping bullet that gives you the best of the AR-15 and AK-47. The Army has already taken delivery of the first batch of SIG XM8 carbines, the carbine variant of that program. Until then, save money with our list of the best AR-15 rifles you can buy for $500. We cannot wait to try one out and let you know what we think. But that won’t be for a good long while…

Not sure which caliber is right for you? Our complete rifle caliber guide compares every major caliber — 5.56, .308, 6.5 Creedmoor, .300 Blackout, and more — with ballistic data, cost analysis, and use-case recommendations.