Replacement for the 556

[<*(((><]

The 6.8 SPC would be a bad joke as a general-issue service round. Lower hit probability than the 5.56, with greater weight (30-40% more, actually weighs about the same as the 7.62x39) and more recoil, too.

Thanks to the AR's 2.26" COL it's limited to stubby bullets. Can't fit the ogive of a sleek, pointy bullet in such a short space. You can either match the speed of the 5.56 with a wiffle ball, or you can equal the 5.56 BCs but go several hundred feet per second slower. The 90 gr XM68GD actually has such a poor BC that 5.56 matches its energy by the time it's gone 200 yards.

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It would be a step backwards towards the 7.92x33 and 7.62x39. All for a supposed (dubious) increase in "stopping power". I think the 6.8 can have a place at short-medium ranges, greater performance from SBRs for close protection, increased power and penetration for hunting, etc. But not as a widespread "5.56 replacement". Intentionally or not, this is reflected in the name—6.8 Special Purpose Cartridge.

110gr+ out of a 6.8 would be what one should judge it on. The 90gr would be CQB (used like the m193). The 6.8 shines at distance (with 110gr+) compared to any mag length 556 in regards to energy and it is close to the drop of the 77gr OTM and the same wind deflection.

Run some numbers on 115gr Federal bullets 0.401bc @2,550fps (16” barrel) against 77gr OTM 0.372 at 2,750fps (16” barrel)

There is a significant energy advantage over all ranges of the trajectory. Hit probability due to increased recoil would be the concern.

 

[mjsdwash]

Ikr, "a 556 has better hit probability than about anything ever made" XD

hit probability being a product of how many rounds can be fired in a given amount of time, at a given range. A 6.5 has lower hit probability because it cannot be fired as quickly as a 5.56. A 22lr has lower hit probability because It cannot accurately reach 100 yards. What damage a bullet does is not as critical as whether or not a bullet makes contact, and the 5.56 can do that better than most other calibers. Thats the system the US has been using for 70 years, like it or not.

 

[Old Guy]

The Brits fielded a .280 cartridge, in a Bull Pup rifle, in 1949? The Yanks said no way and changed the 30-06 for the 7.62X51 round. I watched a Pathe newsreel, full auto, resting buttstock on the chin! The EM2. Emptied the whole mag.
A 3000 ft 5.56 round gets it done. Just take the full auto select lever away. Use hollow points as an alternative?
Was the 20 round magazines used in Vietnam, by US troops, a disadvantage, compared to the AK47 with its 30 round capacity?

 

[mshootnit]

The problem with replacing 5.56 is that it is just so logistically efficient and offers rapid hit probability.
Within a given weight standard, or parameter, you can carry much more 5.56 than even something as small as a 308. So how much less ammo are you comfortable carrying? 15%? 20%?
The 5.56 also offers high hit probability in rapid fire. Recoil becomes a non factor and the user can maintain a near constant sight picture allowing rapid follow up shots.
The rally cry is often to adopt a larger diameter projectile. The question becomes how much of a weight penalty, and firepower penalty do you want to pay for that increased terminal performance beyond 300m?
Potential solutions include advancements in materials or design, as well as the aforementioned diversification of the arms issued, in other words, different tools for different tasks, also the concept of complementary armament within a unit.

 

[entropy]

The Brits fielded a .280 cartridge, in a Bull Pup rifle, in 1949? The Yanks said no way and changed the 30-06 for the 7.62X51 round. I watched a Pathe newsreel, full auto, resting buttstock on the chin! The EM2. Emptied the whole mag.
A 3000 ft 5.56 round gets it done. Just take the full auto select lever away. Use hollow points as an alternative?
Was the 20 round magazines used in Vietnam, by US troops, a disadvantage, compared to the AK47 with its 30 round capacity?

The way the rifles were utilized, yes. Very few soldiers back then had heard of fire discipline, and they had no reason to utilize it with the amounts of ammo available, gunship/fast mover/Arty cover, and quick resupply from a slick. Even when I was in (86-88), far too many were quick to pass the semi position by for 'rock 'n roll'.
The full auto position is useful at times, but it takes training to know when to use it and when not to-they tried to compromise with the 'burst fire' of the A2, and it was criticized by all; muddled up the trigger for semi, and the 'spray and pray' crowd were annoyed at having to re-pull the trigger every 3 rounds.

 

[Hog huntin Harry]

hit probability being a product of how many rounds can be fired in a given amount of time, at a given range. A 6.5 has lower hit probability because it cannot be fired as quickly as a 5.56. A 22lr has lower hit probability because It cannot accurately reach 100 yards. What damage a bullet does is not as critical as whether or not a bullet makes contact, and the 5.56 can do that better than most other calibers. Thats the system the US has been using for 70 years, like it or not.

I researched "hit probability" and there was no mention of the speed in which you send rounds downrange, so please educate me on how quick you can fire your weapon accurately plays into hit probability.

 

[theotherwaldo]

The main reason to replace the 5.56 is the fact that it is an easily reloadable cartridge. This can be a problem when fighting a low-tech opponent.

Anyway, it isn't the weapons or the men on the ground that decided the last several of our wars, it is the will of our leadership that was decisive. Most of the last several wars were left un-won because our leadership directed us to fight to avoid losing, not to fight to win.
No change in ammunition or weapons can be effective if you are not allowed to pursue and destroy your opponent.

 

[Boattale]

The 5.56 cartridge isn’t inadequate. And when you compare our soldiers and their armaments, to other countries likely to be our adversaries, wars/conflicts should be over in a matter of hours or days. Not years. So ask yourself why they aren’t. And there’s where we should be focusing our attention to affect change. Not on a cartridge.

Amen.

 

[Newtosavage]

Amen.

Wars last long as the politicians want them to, period.

 

[Jim Watson]

The main reason to replace the 5.56 is the fact that it is an easily reloadable cartridge. This can be a problem when fighting a low-tech opponent.

The British tried to deal with that over a century ago by banning .450 calibre hunting rifles in India and the Sudan for fear the wogs would use their bullets to reload for stolen Martini Henrys. Sounds kind of far fetched to me, but it generated a lot of odd calibre rifles for the shikari trade.

 

[mjsdwash]

I researched "hit probability" and there was no mention of the speed in which you send rounds downrange, so please educate me on how quick you can fire your weapon accurately plays into hit probability.

are you really saying that having half the amount of available ammunition in any role will not change the likelihood of a hit in combat? Because I don't know how to explain that other than what I just said. here's a video on the basic concept , here is some stuff on Duplex http://www.smallarmsreview.com/display.article.cfm?idarticles=2768, and here https://en.wikipedia.org/wiki/Special_Purpose_Individual_Weapon While these focus on the duplex concept, the principle of lots of bullets still applies.

 

[Shawn Dodson]

The new U.S. military 6.8 cartridge is intended for use against peer adversaries wearing body armor.

 

[TikkaShooter]

It will always be a compromise with a one rifle for everyone stratagy. From the people that I have heard talk about their person experience, the guys that were in Iraq generally don’t seam to have much complaints about their M4/5.56’s, but I’ve seen a lot of people that were in Afghanistan say that they were woefully under ranged with the same combination.

It is more every theater than every strategy.

As a result, the military added the DMR in 7.62N which balanced the game. Balance to the Military means over match.

The 7.62x39 or 5.45x39 ROE isn't much different than the 5,56 except the 5.56's range is longer.. An essential difference between the doctrine of the Com block and the West is they embrace mass or spray fire and the West embraces aimed fire.
The Muj gave the Russians a fit with WWII .303s. The proverbial longer range with a "shoot and scoot" rule of engagement worked quite well. The 7.62N balanced the equation for our war fighters.

The 6.8 adds more range to the 5.56. In addition, it is a cheap date; or swap an upper and not the whole platform. The real problem, the so-called planners always plan for the next war based on the last war. Although that may not make sense; it is what they do. OTOH, any more powerful upper on the existing 5.56 lower would work and quite well.

 

[Hog huntin Harry]

are you really saying that having half the amount of available ammunition in any role will not change the likelihood of a hit in combat? Because I don't know how to explain that other than what I just said. here's a video on the basic concept , here is some stuff on Duplex http://www.smallarmsreview.com/display.article.cfm?idarticles=2768, and here https://en.wikipedia.org/wiki/Special_Purpose_Individual_Weapon While these focus on the duplex concept, the principle of lots of bullets still applies.

No sir I didn't mean that, but since the 556 right now is the most balanced cartridge for military use let's just put this argument to rest. Btw very informative video.

 

[TikkaShooter]

The way the rifles were utilized, yes. Very few soldiers back then had heard of fire discipline, and they had no reason to utilize it with the amounts of ammo available, gunship/fast mover/Arty cover, and quick resupply from a slick. Even when I was in (86-88), far too many were quick to pass the semi position by for 'rock 'n roll'.
The full auto position is useful at times, but it takes training to know when to use it and when not to-they tried to compromise with the 'burst fire' of the A2, and it was criticized by all; muddled up the trigger for semi, and the 'spray and pray' crowd were annoyed at having to re-pull the trigger every 3 rounds.

X2 and you nailed it. True, but as a result in time, the spray and pray crowd were issued 3 round burst. Instead of point it in the general direction and spray away; they learned "fire control discipline."

I used to live near Ft Bragg. As the schools were better and the neighborhoods were safer than "Fayette-Nam." A lot of my neighbors were SF who threw great parties. One of the reasons for 3 round burst was the amount of ammo expended on FA in Grenada.

 

[mjsdwash]

No sir I didn't mean that, but since the 556 right now is the most balanced cartridge for military use let's just put this argument to rest. Btw very informative video.

Good way to put it, "556 right now is the most balanced cartridge for military use" was exactly the message i meant to convey.

 

[DustyGmt]

I cant imagine a better all purpose round for the military than a 5.56. I've heard 77gr 5.56 at extended ranges on human targets is outstanding, 1 shot incaps.

 

[d2wing]

The way the rifles were utilized, yes. Very few soldiers back then had heard of fire discipline, and they had no reason to utilize it with the amounts of ammo available, gunship/fast mover/Arty cover, and quick resupply from a slick. Even when I was in (86-88), far too many were quick to pass the semi position by for 'rock 'n roll'.
The full auto position is useful at times, but it takes training to know when to use it and when not to-they tried to compromise with the 'burst fire' of the A2, and it was criticized by all; muddled up the trigger for semi, and the 'spray and pray' crowd were annoyed at having to re-pull the trigger every 3 rounds.

Sorry but I am a Vietnam veteran. I resent your comment that we never heard of fire discipline. We most certainly did. We were trained to use short bursts for better fire control. It is pretty easy to criticize when you weren't there. So many assumptions made by guys that were not there.
Much research went into the adoption of the 5.56 concerning lethality at combat ranges, hit probability, range and controllable rate of fire and well as combat load which is much more than just ammo. The problem is finding a cartridge that significant improves in major areas with losing something in other areas. One thing you don't get that lethality is directly related to cartridge velocity and rate of fire. You may think otherwise but your opinion doesn't count. Only results in research and actual combat do. Any increase in bullet weight will decrease range, rate of fire, and lethality at most combat situations. However some kinds of fighting require a significant increase in mass and energy. Like barriers and very long range. A moderate change to the current cartridge isn't going to be enough. The military continues to want a one weapon approach, which is a major reason for the M-16 in the first place. In my day some units had a sniper with a actual sniper rifle and there were M-60's.. My buddy carried a modified and scoped M-14. Current military like in my day considers the use of quick response air support and supporting artillery. The problem is they aren't there when you need them way too many times. I think a multiple weapon approach is needed.

 

[Newtosavage]

Sorry but I am a Vietnam veteran. I resent your comment that we never heard of fire discipline. We most certainly did.

This the problem with reading comprehension and the internet these days. He never said "none" of the soldiers back then, and certainly didn't say you in particular. What he said was "very few." So if you and your buddies had heard of fire discipline, then you were not included in his comment. No need to be offended or feel resentful.

Carry on.

 

[entropy]

True, it was only second-hand knowledge, heard from many who had been there; neighbors, co-workers, the senior NCO's I served with. And as I said, it was not uncommon when I was in later for some to bypass semi and go straight to full. I did not mean to imply that any one individual had done so, merely that there were more than a few who had. I am definitely in agreement with the multi-weapon approach you suggest.

 

[d2wing]

Sometimes full auto is fire control. When your surrounded outnumbered and can't see them in heavy cover, you fire for effect. Rate of fire as in loudest side wins. They made them in full auto for a reason. It truly upsets me when guys say judgmental things about guys that outfought the fanatic brutal enemy on their turf and won the battles. Actually our guys had skills that modern fighters don't have in some respects. Back then guys were drafted or had short enlistments. And a higher percent were already skilled rifleman, Now the are career soldiers and training is different. Now soldiers rely on optical sights more. The way guns are used has changed a great deal since then and of course the battle grounds are different. What worked in the jungle might be different than in the desert or urban warfare just as weapons and doctrine were very different in World War two and Korea. While the 5.56 and AR rifles and carbines are pretty ideal in high rate of fire or aimed fire at skinny people in normal combat they are not well suited to barriers, very long distance and armored soldiers.

 

[d2wing]

This the problem with reading comprehension and the internet these days. He never said "none" of the soldiers back then, and certainly didn't say you in particular. What he said was "very few." So if you and your buddies had heard of fire discipline, then you were not included in his comment. No need to be offended or feel resentful.

Carry on.

No I comprehend just fine. He said very few. That 's pretty inclusive. Full auto was part of the doctrine at the time. it wasn't lack of fire control. Get back to me when you have comprehension.

 

[MikeInOr]

I have always considered the 6.5x55 to be one of the best military rounds. Very soft shooting but packs a lot of punch. I believe the 6.5 creedmore to be pretty close but have never shot a creedmore myself.

As far as off the shelf rounds I would take a .243 battle rifle over a .223. Both soft shooters but the .243 has a back of a lot more punch for not that much bigger a cartridge.

The 6.5 General is another cartridge that I would find preferable but is even closer in size to a 223.

I guess I am just one of those old guys that will always consider the .223 a varmit round and not really optimum for much else.

 

[Robert]

Ug, this one makes my head hurt. The military doesn't care one bit what we think and their policy is no concern of THR.