Weapons of the World: Little Bullets (5.56) Lose Respect

Weapons of the World ^ | November 15, 2005

[holymoly]

November 15, 2005: The U.S. Army’s cancellation of the XM8 (a replacement for the M16) reflects disenchantment with the 5.56mm round, more than anything else. While the 5.56mm bullet was OK when used in an automatic weapon, it is much less useful when you have so many troops who know how to shoot, and can hit targets just as easily with single shots. In addition to better shooting skills, the troops also have much better sights, both for day and night use. It’s much more effective to fire less often, if you have troops who can do that and hit what they are shooting at with the first shot. Most American troops can.

Moreover, the 5.56mm round is less effective in urban fighting, where you often want to shoot through doors and walls. The 5.56mm round is not as effective at doing this as is the heavier 7.62mm bullet. And the troops have plenty of 7.62mm weapons available, in order to compare. There is the M240 medium machine-gun. While this 7.62mm weapon is usually mounted on vehicles, it is often taken off and used by infantry for street fighting. Lots of 1960s era 7.62mm M14 rifles have also been taken out of storage and distributed. While used mainly as sniper rifles, the snipers do other work on the battlefield as well, and the troops have been able to see that the heavier 7.62mm round does a better job of shooting through cinder block walls, and taking down bad guys with one shot. Too often, enemy troops require several 5.56mm bullets to put them out of action.

In a situation like that, it makes more sense to carry a heavier round. The question is, which one? The army has been experimenting with a 6.8mm round, but now some are demanding that the full size 7.62mm round be brought back. There are M16 type weapons that use the full size 7.62mm round (and the lower powered AK-47 7.62mm round). The new SOCOM SCAR rifle can quickly be adapted to using all of the above by swapping out the barrel and receiver. Could be that the army is going to wait and see what SOCOM decides to do.

The other big complaint about the M16 is it’s sensitivity to fine dust, as found in Iraq and, to a lesser extent, Afghanistan. This stuff causes the rifle (and the light machine-gun version, the M243), to jam. Troops have to be cleaning these weapons constantly. Another problem with the M243 is that most of the ones in service are very old, and in need of a replacement (with new M243s, or a new weapon design.) The XM8 solved much of the “dust sensitivity” problem, but part of the problem was the smaller round.

A decision on the army’s new assault rifle will probably come sooner, rather than later, because the troops fighting in Iraq and Afghanistan are making a lot of Internet noise over the issue.

[Spktyr]

Clint at Fulton Armory has a lot to say about them. They have soft bolts, soft barrels, a host of other problems...

[elbucko]

The other is the wound factor. It is a fact that if there is a wounded soldier, it takes two or three others out of action to take care on them...one of the reasons 5.56 was created.

This is an old-wives-tale and needs to be divorced along with the old wives that spread it and the M-16 x 5.62 that it rode in on. American soldiers don't shoot to wound, so why should their combat rifle? The idea that Muslims or communists are going to waste manpower on caring for the wounded is ludicrous. The one main reason we are fighting these people is that they are animals. They don't care for their casualties, their countries or their societies.

[sit-rep]

Got the brow beating yesterday so sit down Francis...

When one openly states they have never seen combat, it is not necessary to keep shooting...lol...

[razorbak]

Would a 6.8 be about the same as the .270? I have long thought that if we up-sized our ammo that the .270 would be about as powerful as the .308, and a little flatter shooting and lighter than the .308 [7.62]. Unless I'm mistaken, isn't the .270 a short action cartridge like the .308?

[MrEdd]

Got the brow beating yesterday so sit down Francis...

His mother called him Francis....once.

[razorbak]

So much for my rifle cartridge knowledge. It's the .270 Wincester Short Magnum that is a short action round. Maybe it could be modified to work in U.S. military assault rifles. If not there are the two excellent short action rounds, the .308 and the .243.

[sit-rep]

I would think... I flagged some folks in who do know...

[faq]

I hope the Army goes ahead with the XM8. It's time to replace the M16 with something better. There have been a lot of good reasons given here to choose either the 5.56 or the 7.62. But really, why does it have to be one or the other? Design the XM8 so that it can be chambered for either round. (Right now a person can buy a Browning BAR in about a dozen different calibers.)
I mean, I've got three rifles in my gun cabinet, why should a soldier be limited to only one gun. Let the military order some of both, hand them out as needed for the situation.

[OKSooner]

Later read.

[verity]

If this information is correct, the XM8 has been put on hold indefinitely.

XM8

[Squantos]

Keep a Mk 1 Mod O eyeball out for new weapon designed "around" the 6.5 grendel ....not a current caliber being stuffed and crammed into a current weapon system......that's my SWAG on the matter !

Write it down .....:o)

[sit-rep]

(My best David Lee Roth...)

Gimmie somthin' to write on man!!!

[Squantos]

lol

[planekT]

I looked that up today (Gyro Jet). Very intersting. Seems like with a few refinments, it would work. A cartridge that leaves the barrel at a relatively slow pace and then picks up steam as it goes along is very intriquing.

I also found some stuff on liquid fueled rockets. You're right, there are some serious problems. Heat for one. 2,500 degrees and up. What would that do to a gun barrel? Liquid rocket fuel is also unstable compared to solid fuels, plus it's very corrosive. Apparently at some point the availability of Hydrogen Peroxide dried up, and people are no longer building rocket engines in their garages as they once did not so long ago.

Back to the drawing board. Propellants or methods of propelling a bullet are probably as good place to start as any. Some mentioned in earlier posts about using a 72 grain bullet for the .223. Actually Black Hills Ammunition came up with a round for our Special Forces in Afghanistan which weighs 77 grains. Obviously they needed a propellant that would stabilize the heavier bullet wihout creating exceedingly high pressures. I bought a box of their Cowboy loads not knowing what it was, so that's how I came across them.

Thanks for the reply. This really is an intersting subject.


P.S. Those cowboy loads were kind of cute. Very light recoil and they even throw off a little smoke for that cowboy effect. :-)

[Arioch7]

I do not really like the round but here is what an Infantry Officer has to say about it when I asked him if he liked the 5.56 round and the M-16...

Its fine. small size of the round enables high magazine capacity. little recoil enables accurate, quick sustained fire. the slight recoil also contributes significantly to marksmanship. the damage with the small diameter round is caused by yaw, or bullet tumble, due to the high velocity of the round... or so some say...

I like the round for its accuracy charecteristics... and having witnessed for my own eyes "average" soldiers from other nations shooting side by side with U.S. soldiers... I can tell you this is a fact... american marksmanship is far superior to that of any "average" soldier from any other army I have seen... we train good shooters fast, and the slight recoil surely helps...

the round is at its best, like any round, for center mass hits... works well for your "average" malnourished terrorist at "average" ranges... In truth, however, I don't think the round would perform too well against an! enemy wearing body armor or even one that was wearing heavy cold weather gear...

Arioch7 here. There you have it. Personally, I have owned an AK-47 and appreciate that gun and the M-14 more but there are pros and cons to all things.

I still liked my AK though...

[Tailback]

I hope the Army goes ahead with the XM8. It's time to replace the M16 with something better.

While the gas system of the XM-8 is better than the M-16's direct impingement system, the XM-8 still has one fatal flaw. It is designed to accept M-16 magazines and the magazine well limits the overall cartridge length of any future caliber to the same as the 5.56 NATO. The 6.5mm Grendel has perfect ballistics but the shape of the case may make it unreliable in full auto or burst mode. (I don't know, it needs testing) The replacement for the M-16 family needs to be a 6.5mm-7mm bullet with ballistics similar to the Grendel, 6.5 Mauser, .260 Remington etc.... If you could lengthen the case of the 6.8 SPC to bump up the velocity it would be great, but that round was and is limited by the M-16 and XM-8 magazine well.

[hiredhand]

The .270 is a LONG action sort of cartridge. Somebody can correct me if I'm wrong, but I'm fairly certain that it's based on the .30-06. The good ole .30-06!

Also based on .30-06 is .308 Win (A.K.A. 7.62 NATO...pretty much), and .243 Winchester is based on .308 Win. As a matter of fact, I've run .308 cases through the .243 die, and created .243 cases! I think there's supposed to be a "step" die, and it probably wasn't the "nicest" thing to do with a thick MILSPEC .308 case, but it DID work!

A qualified ballistician could probably go into a LOT more detail than I can here, but here's how I understand this whole "5.56mm VS 6mm" debate.

First off, from what I've read it seems that selection of the 5.56mm (.223 Remington) was a political decision. Only now, some 30 years (or more) later are politicians catching up to the fact that the 5.56mm round is generally underpowered and not very good at stopping man sized targets at even moderate distances.

Most states in America don't PERMIT hunting with the .223 Rem round because it just doesn't knock down deer sized critters! Yet, it's our standard service round for rifles! Go figure. :-)

The whole reason the 7.62 NATO round was adopted was because it was discovered that with bullets up to 150gr, equal performance to .30-06 was achieved. THIS is a true! Since it's a shorter cartridge (by some 8mm if I remember correctly), a soldier could carry more ammo. At one time, the DoD had either adopted the M-14, or was thinking about it. As I remember it, the M-14 beat out the FN-FAL but not by much. I don't know much about those details.

Anyway....about the "debate". The whole problem is mostly presented in a factor known as a "ballistic coefficient". Otherwise known as the BC. The BC of any given projectile is it's ability to overcome all exterior forces and stay aloft at an acceptible velocity. BC is usually expressed in decimal numbers because a BC of 1.00 is LIFT! NO projectile fired from small arms has a BC equal to 1! Technically, all projectiles start falling shortly after leaving the barrel! A high BC would be .500. A low BC would be .300 to .100 or so.

To give you a more realistic example, 110gr .308 FMJ bullets have a BC of .144. 200gr .308 Spitzer bullets have a BC of .556! As you can probably guess, the heavier Spitzer will have a much "flatter" trajectory! Unfortunately, it also has a MUCH slower muzzle velocity on account of its weight!

So what to do? Smaller, lighter bullets have LOW BCs and are relatively ineffective at typical "contact" ranges for infantry riflemen. Heavier bullets have HIGH BCs, but travel slower.

The answer is to find the "ballistic match". A ballistic match is a combination of three things which produce as near a perfect cartridge as possible. Currently, there are TWO known (agreed upon) ballistically matched cartridges. One is the .30-06, and the other is the .50BMG. Given their case capacity, bore diameter, and suitable, available propellants, these cartridges are both as close to perfect as we can get.

Notice, I mentioned that propellant as a factor in a ballistically matched cartridge! Since propellant technology has advanced in the past 20 years, there are other (disputed) ballistically matched cartridges now as well. These use mainly 6mm (.243) and 6.5mm projectiles. The reason being is that a high BC can be maintained, along with sufficient weight, in order to deliver a lot more energy onto a target. For example, a HEAVY 5.56mm bullet weighs 70gr and has a BC of .214. NOT very impressive. It will exit muzzle at approx 2800FPS. A HEAVY .243 Win (6mm) bullet will weigh 110gr and exit muzzle at the same velocity, but it has a BC of .443!

I haven't looked up the differences in energy delivered by 5.56mm as opposed to 6mm projectiles at distance, but as I remember the differences are BIG! The heavier 6mm bullet flies a much flatter trajectory, has a farther midrange trajectory, and delivers SIGNIFICANTLY more energy onto the target!

The bottom line in this issue is that the 5.56mm projectiles simply don't have enough mass to transfer sufficient energy for a "knock down". Heavier bullets only produce less velocity, and since it's bore size is so small, there hasn't been a propellant designed yet to overcome this problem. It's not likely that somebody will design one for this purpose either!

One the other hand, 6mm, and 6.5mm cartridges permit slightly slower burning powders, a wider range (including HEAVIER) bullets, and identical velocities using these heavier bullets! A 6mm or 6.5mm projectile is a great choice IMHO. I'd personally love to see our soldiers carrying weapons firing the .243 Win on the battlefield.

From what I've read, planners are leaning toward 6mm cartridges not only for reasons I wrote about above, but because it's feasible to control a select fire weapon chambered for cartridges such as the 6mm Remington, .243 Win, and 6.5mm Remington. I'm a GREAT fan of .308 cartridges, but it's a FACT that .308 infantry weapons (such as the M-14, and FN-FAL) can be DIFFICULT to control using full auto. Especially from any non-supported stance. A LOT of ammo gets wasted.

As for the 6.8mm round. I've only read a little about the development, and experiments. From what I've read, they're trying to get the "best of the best", and a 6.8mm projectile seems to be IT. From what I know about 6mm rounds so far, I suspect they may be onto something.

I hope this cleared things up a tad. As always, it's my opinion only. A collection of ramblings and rants based on observations, and readings over the months and years. :-)

[Squantos]

6.5 Grendel........:o)

[Spktyr]

I looked that up today (Gyro Jet). Very intersting. Seems like with a few refinments, it would work. A cartridge that leaves the barrel at a relatively slow pace and then picks up steam as it goes along is very intriguing.

The problem is that that means that the low velocity projectile won't cause much damage at close range, and can easily be blown off course. An all-burned-on-launch type would have prodigious recoil and dangerous back/muzzleblast. Rocket exhaust tends to be spectacular, hot, and stupendously toxic.

The next leap forward in infantry weapons development will be the man-portable railgun, IMHO. The only problem is the power supply (which could be contained in a magazine).

[JCEccles]

Moreover, the 5.56mm round is less effective in urban fighting, where you often want to shoot through doors and walls

Which is why, when the Marines went calling on a hunkered-down enemy in World War II, they were pleased to use John Moses Browning's lil' door knocker with .30-06 knuckles: