Since its introduction there have been critics of the 5.56 NATO cartridge. It’s an overgrown .22, a varmint cartridge, not a real battle rifle cartridge. This is the sentiment mirrored by retired Army Maj. Gen. Robert Scales and others in the armed services Senate Committee.
“Since the end of World War II the richest and most technologically advanced country in the world has sent its soldiers and Marines into combat with inferior small arms,” said Scales (.pdf). “So inferior, fact, that thousands have died needlessly. They died because the Army’s weapon-buying bureaucracy has consistently denied that a soldier’s individual weapon is important enough to gain their serious attention”
Concern over the capabilities of 5.56 NATO has risen since the introduction of a new, low-cost grey-market body armor. Senator Joni Ernst (R. Iowa) asked General Mark Milley if the military was looking into a commercial alternative or a military-specific option to deal with emerging threats.
“I don’t know if the two are mutually-exclusive,” said Milley. “There are systems out there today on the shelf, that with some very minor modifications, could be adapted to munitions that we’re developing in Fort Benning that could be used to penetrate these SAPI plates that our adversaries are developing.”
“It’s not necessarily an either-or proposition on that one,” he stated.
The military is working on new bullet designs beyond what is being fielded and even tested today. These bullets can be used to make 5.56 and 7.62 NATO cartridges as well as just about any other suitably-sized ammunition.
What Milley is talking about is probably not based on the M855A1 Enhanced Performance Round or its 7.62 variant. That is already in the field and in limited service. It could be the XM1158 Advanced Armor Penetrating (ADVAP) family of 5.56 and 7.62 NATO cartridges.
As far as defeating inexpensive body armor, it doesn’t sound like the military is too concerned about rolling out a new cartridge and making changes to all the weapon systems that use 5.56 NATO.
That said, recently multiple branches of the military have looked at cartridges chambered in the 6-6.5mm range for specific purposes and possible wide-range fielding. And the Army just fielded a notice for an M249 replacement that opened the door for a new mid-range cartridge option.
On the one hand, a mid-size 6mm cartridge could be fielded as a do-all round. But it would be necessarily heavier than 5.56 and require a lot of painful changes in logistics.
It sounds like the military is still developing improved 5.56 NATO projectiles, which means the cartridge is here to stay for the foreseeable future.
With a few trivial changes to the M4, such as a longer, better-profiled barrel and free-floating handguard, the military could easily and inexpensively push 5.56 NATO out further and make soldiers more effective. With modern hardware and the right training, high sectional density 5.56 has a much longer reach and improved armor-piercing properties.