For nearly three decades 5.56mm NATO M855 Ball (inset, left)…

For nearly three decades 5.56mm NATO M855 Ball (inset, left) has been the standard service load for the M16 rifles and M4 carbines carried by most American infantrymen, as well as M249 and Mk46 light machine guns used by conventional and special forces. These weapons can be converted to fire the 6.8mm SPC (inset, right), which delivers superior terminal effects against both soft and hard targets. Courtesy of U.S. Air Force.

In comparison to conventional units, special operations forces (SOF) have traditionally been given much wider latitude in regard to the weaponry they can use. A perhaps inevitable consequence of this fact is that Special Operations Command (SOCOM) is allowed to develop combat weapons and ammunition independently of the Army’s small arms programs.

One of SOCOM’s endeavors was the Special Purpose Rifle (SPR), a heavy-barrel, “accurized” version of the M16. Equipped with a telescopic sight, the SPR has been used in Afghanistan for engagements at distances beyond what is feasible with the standard M4 carbine. Firing Black Hills’ Mk262 competition ammo loaded with a 77-grain, Sierra MatchKing bullet, SOCOM units have reportedly hit Taliban and al-Qaeda targets at ranges in excess of 600 yards.

The 5.56mm “Optimized” round, created specifically for the short-barrelled Mk18 carbine, is loaded with 70-gr. Barnes TSX bullets (inset, left). Comparable 6.8mm loads are available with the 110-gr. TSX (inset, right) and 85-gr. TSX. Courtesy of U.S. Navy

Some SOF veterans of Somalia in 1993, and Afghanistan a decade later, were dissatisfied with the fight-stopping ability of the standard 5.56mm M855 Ball round when fired from the M4 carbine. Better results have been reported by special operations soldiers who have used the Mk262 load in the mountains of Afghanistan. However, even the improved terminal effects of the 77-grain loading did not satisfy some SOCOM personnel, who pushed for the creation of even more lethal ammunition.

The M249 light machine gun fires the 5.56mm projectile (inset, left), which has proven to have less than stellar tactical penetration against barriers commonly encountered in urban combat. Converting the M249 to fire 6.8mm (inset, right) would significantly improve the ability to defeat “hard” targets. Courtesy of U.S. Army

For improved terminal performance of their M4A1 carbines, U.S. special operations personnel have been using 5.56mm Mk262 ammo, which is loaded with a 77-gr. Sierra MatchKing BTHP bullet (inset, left). In a quest to provide even better effectiveness, the 115-grain Hornady BTHP (inset, right) was developed for use in the initial 6.8mm SPC combat load. Courtesy of U.S. Air Force

Load Comments
  • Chris G

    After reading your article and what I have recently read about what is happening in OEF (afgahnastan), it almost made me sick. As a Veteran of two trips to Iraq with 2 yrs patroling bahgdad and another 3 months in Southern Iraq kicking IEDs. When someone of your reputation jumps onto a bandwagon, it can cause unneccesary harm. Allmost everything I’ve recently read has indicated that most of the Insurgents are hanging up at or over 700-800M (meters) from our guys. Yes there is a problem with the 5.56, I’ve seen it first hand. But when you toute the 6.8 as the cure all that is far from true. It will work as advertised up close in the confines of a house, and I would appreciatte it for it’s limitations and excelence in CQB, and out to 300M, but beyond 400M it’s accuracy from all the data I’ve read is’t commonly acceptable for that range and beyond. Beyond 300M, it’s trajectory fall from a cliff, that is somewhat better than a 30-30. Energy bleeds off like ice setting on a hummer hood in the summer in Iraq. If you want to maintain the Lower recievers in an AR-15/M-16/M-4, lineup compromise will need to be made at some exspense. Right now the Venerable M-14 is being pulled out of Military Storehouses as fast as possible, and turned into DMRs. Instead of our soldiers carrying Saws, they are packing M-240s, cause these weapons have the punch to reach these extended ranges Hadji’s hanging up at while firing his 7.62x54R at us. The 6.8 shoots a farly stubby 118 gr projectile that has been shown to be tempermental with chambering and throat length. Everything I’ve read on another cartridge is showing it may suffer slightly at CQB ranges, but would still be superior to the 5.56, is the 6.5 Grendel, it launches a 123gr projectile that has a considerably higher BC (Balistic Coefficent), than the 6.8, and this projectile is launched faster than the 6.8. So not only will this round maintain it’s speed/energy longer, it starts out with higher amounts of both. This round actually maintains it’s velocity better than a 7.62 round. It has the ability to be combat effective out to the above ranges and cause significant wounding. This is just what we need, as soldiers in a war environment, it’s not perfect, but it’s better than the 6.8. The british were looking at a simular round back during the vietnam war, and the U.S. told them to redo it in one of our compatable chamberings. If you really want to streamline Ammo manufacture, you can have your Light Machine guns fire the 6.5 Grendel, and your heavier Machine guns fire the 6.5 Creedmore, which at those above ranges is flying flatter faster and is retaining more energy than even a 7.62 Nato round. the Military is looking for thier next generation of weapons, and as my time in the military wanes towards my retirement, I want to know that the soldiers that I helped train once they got to a unit I was in will recieve a better generation of weapons able to handle these situations better than it’s current one. Instead of listing this Cartridge as the do everything singing and dancing, you should also have listed off that it has been seen to have range limitations as far as combat accuracy has shown, and it’s overall range limitations, shame on you.

  • Matt in Oklahoma

    There’s nothing wrong with either of those General. But someone wouldnt make extra money off of Uncle Sugar by using an exsiting round!

  • General Jim M

    6.8? What is wrong with the 243 Winchester or the 6mm Remington?People are always spending big money for a solution that already exists.For some reason i like the 6mm Remington more than the 243 but Remington does not back it like the 243 is backed.It’s hard to find any 6mm rifles and chain stores don’t put 6mm Remington on sale during hunting season like ammo companies put the 243 on sale.Today,since the twist rate of the 6mm was changed long ago the 6mm is actually slightly superior to the 243.For handguns? The 10mm auto!!!!!