Posted on 02/02/2007 12:23:59 PM PST by John Jorsett
Troops from the U.S. Army and Marine Corps are still complaining about the "inadequate stopping power" of the 5.56mm round used in the M-16 family of assault rifles. Last year, the army did a study of current 5.56mm M855 round, in response to complaints. Troops reported many reports where enemy fighters were hit with one or more M855 rounds and kept coming. The study confirmed that this happened, and discovered why. If the M855 bullet hits slender people at the right angle, and does not hit a bone, it goes right through. That will do some soft tissue damage, but nothing immediately incapacitating. The study examined other military and commercial 5.56mm rounds and found that none of them did the job any better. The study concluded that, if troops aimed higher, and fired two shots, they would have a better chance of dropping people right away. The report recommended more weapons training for the troops, so they will be better able to put two 5.56mm bullets where they will do enough damage to stop oncoming enemy troops. Marines got the same advice from their commanders. But infantrymen in the army and marines both continue to insist that the problem is not with their marksmanship, but with the 5.56mm bullet. Marines say they have used captured AK-47 rifles in combat, and found that the lower velocity, and larger, 7.62mm bullets fired by these weapons were more effective in taking down enemy troops.
The army study did not address complaints about long range shots (over 100 meters), or the need for ammo that is better a blasting through doors and walls. The army had been considering a switch of a larger (6.8mm) round, and the Special Forces has been testing such a round in the field. But a switch is apparently off the table at the moment. The army report was not well received by the troops, and there is still much grumbling in the ranks over the issue.
When I was medivaced my rifle stayed on the boat. A US Navy passenger going back to Da Nang was given it to use for the fight back down river. When I returned from the hospital I saw a nice line of holes in the canopy. It seems no one told him it was full auto. He took careful aim with the rifle laying gently in his left hand. He squeezed the trigger. He fired of 20 rounds at full auto.
He sat behind the sandbags the rest of the trip.
Thanks for your service to our country !
1 - A .30 cal battle rifle will NEVER be adopted as the issued arm for the US military again, it just won't happen. A few in some units will be issued M-14's and AR-10's or some thing in 308 but the idea that anything in .30 caliber will replace the M-16 is a nonstarter.
Probably correct so long as we have ± 15% female troops. At least for as long as conventional cartridge weapons remain the state-of-the-art; there are some liquid-fueled cartridge prototypes that are getting close to the requirements for practical use, but there are still a couple of materials breakthroughs needed.
2 - The logistics folks have spoken and apparently killed the 6.8SPC, I don't know how serious the Army or other branches were about a new round but it seems it didn't matter.
Yep. Though it seems that SOCOM, at least, is going to get a new .40 S&W caliber [no doubt with a NATO metric designation that'll take around 24 months for full approval] handgun to replace the M9 Beretta...probably a Glock 23 or thereabouts.
3 - The 6.5 Grendel has virtually no taper and I don't think was ever a serious contender because of that, Great ballistics though.
Interesting and reasonably effective with a 15-inch M4 carbine. But both the Army and Navy played with .243/6mm and 6.5 variants of the 5,56mm cartridge when the JSSAP tests of the M16A2 were going on around 1979-80. And the Grendel is less well-suited to belt-fed use with the Squad Auto Weapons, though barrel changes take all of about five seconds. One thing that might bring about at least limited use of the 6,8mm cartrridge though: If the Russians start rebarreling AK103s and AK74s [and RPK74s] for a .270-.276 diameter bullet loaded 5,45x39.5 round.
4 - The wounding and killing characteristics of the 5.56 under 100 yards apparently is not the problem, this is with 55, 62 or 77 gr. bullets. The majority of complaints apparently only concerns shots over 100 yds. out of weapons that usually have shorter barrels. The lower velocity has the bullets falling below the velocity that allows the round to fragment prior to hitting enemy combatants therefore the pencil hole wound rather than the tumbling, fragmenting wound that puts people down and out of the fight.
Effectiveness against folks with body armor is another particular concern. So is cold-weather performance. Ever notice how we're always so experienced and well-prepared to fight the last war, but never the next one? And if we ever go up against light armoured vehicles, or effectively hardened *technicals* as in Somalia again....
5 - The majority of ammo in 7.62x39 currently on the battlefield has you shooting howitzer trajectories beyond 100 yds.
It gives a heck of a beaten zone with the 24-inch barrel of the RPK though. Considering that the 7,62x39mm M43 [as in M1943]cartridge was developed to replace bolt-action rifles that shot a cartridge adopted in 1891 [and that's STILL used in SVD sniper's rifles and PK machineguns] and pistol-caliber PPSh and PPS burp guns, the old AK loading has earned its keep. And some very qualified users who have their choice of older AKMs or newer 5,45mm AK74s pick the one that pushes the big heavy bullet every chance they get.
If we can agree that some of the above is true perhaps not ideal be true, maybe a reasonable debate can ensue. Finally, not trying to thread hijack, but what, (I know the logistics folks would have a fit with this idea also but) would the learned gun folks on FR think about retiring the current M24 and M40's in 038 and replacing them with new rifles chambered in 300 WSM. The Army is still using the M24 a long action in 308 with the pretense that can rebarrel to .300 Win Mag, well I counter if you were ever going to up to the Win Mag, Afghanistan and long desert shots in Iraq would have been the time. The Marine Corps uses the M40 and short action, but if you can get a few hundred fps over the 308 out of the same size rifle I'd think it would be the way to go. What say you all?
The Navy looked real, REAL hard at the .300 Win cartridge, long a Navy Palma Match Team favourite, during the development of the Navy M86 sniper's rifle, hopefully swiping the best from the Army M24 and the Marine M40A1/A2. And stuck with the 7,62 NATO chambering, in part for commonality with the platoon LMG [and the Navy is tinkering REAL hard with a 7.62 SAW, the Mark 48, mod 0] If more than a 7.62 is needed, it probably ought to be a .338 Lapua....and probably on the L115A1 AWM rifle platform, as per the Royal Marines issue.
One of the interesting armourer jobs I got while recovering from a badly-infected small arms hit to my lower back was grinding the bayonet lugs off some 200 early M16 rifles being handed over to our Vietnamese ARVN allies as American forces were getting M16A1s. The rifles were to be fitted with XM148 40mm grenade launchers, and it seems that during the Tet '68 fighting, one earlier ARVN grenadier fired off his XM148 with the bayonet locked in place on his rifle.
Ooops.
Opps, I reread what you wrote about the adoption of the 7.62x39 and yes you're correct about the timing and such. The bigger bullet hitting harder is kind of the point of the thread and the x39 does do the job. When in doubt read it again I ought to slow down on the quick post reflex.
It was my pleasure.
...one earlier ARVN grenadier fired off his XM148 with the bayonet locked in place on his rifle.
Oops!
Oops!
The technical term for such events is *A bad day at the office.* The high explosive grenade for an M79/XM148/M203 is supposed to be safe until the spin from the rifling gets it up to about 400 rpm, at which point it arms itself to detonate upon contact. The later M386 H.E. round differed from the earlier M381 and M441 rounds in that it had a longer arming distance of 14-28 meters compared to the 2-3 meters of the M381 and M441- which was probably what that poor goof with his new underbarrel XM148 was using.
But do not bet your life on the safing distance of any 40mm round, particularly in brush or woodland. It only has to go off too close to you only once.
But do not bet your life on the safing distance of any 40mm round...
As evidenced by Hanoi John’s first “Purple Heart” at Cam Rahn Bay.
Wounding Effects of the U.S. Military M193 (M16A1) and M855 (M16A2) Bullet Cartridges
Exaggerated descriptions of the wounding effects of the M16 rifle bullet flourish as great works of urban lore. One fable describes a bullet that tumbles end-over-end in flight as soon as it exits the muzzle of the rifle. Another legend provides a dramatic account of an unstable, super-high velocity bullet that tumbles and chews its way through flesh like a buzz saw. Although there appears to be a tinge of half-truth behind these entertaining and awe-inspiring mythical tales, these stories do not represent an accurate description of the wounding characteristics of the M16 bullet.
When the M16 cartridge is fired and the bullet is propelled down the bore, the bore’s rifling imparts a gyroscopic spin to the bullet. This gyroscopic rotation is needed to maintain point forward stabilization of the bullet as it flies through the air. This method of bullet stabilization is identical to the rotational spin applied to a football when thrown by a quarterback (American football).
The Earth’s gaseous atmosphere is approximately 400 times less dense than the body's soft tissues. When the M16 bullet strikes and plows into the body, the rotational spin that stabilized its flight through the air is insufficient to maintain its stability as it flies through dense tissue. The bullet typically penetrates point forward for approximately 4-5 inches before it begins to seek a state of stability in the body.
The bullet’s pointed shape makes it heavier at its base than its nose, producing a center of gravity that is located aft of its longitudinal centerline. When the bullet hits the body and penetrates, the bullet attempts to rotate 180 degrees around its center of gravity to achieve a base forward orientation. This backwards orientation is the bullet’s stable position in tissue because it places the center of gravity forward.
As the bullet yaws through 90 degrees and is traveling sideways through flesh, the stress of tissue resistance to bullet passage can overpower the physical integrity of the bullet. The bullet has a groove around its midsection called a cannelure. The purpose of the cannelure is to permit the mouth of the cartridge case to be crimped tightly against the bullet shank to hold it firmly to the case. The cannelure weakens the structural integrity of the bullet's copper jacket.
At distances of 100 yards and under, when the bullet hits the body and yaws through 90 degrees, the stresses on the bullet cause the leading edge to flatten, extruding lead core out the open base, just before it breaks apart at the cannelure. The portion of the bullet forward of the cannelure, the nose, usually remains in one piece and retains about 60 percent of the bullet's original weight. The portion of the bullet aft of the cannelure, the base, violently disintegrates into multiple lead core and copper jacket fragments, which penetrate up to 3-inches radially outward from the wound track. The fragments perforate and weaken the surrounding tissues allowing the subsequent temporary cavity to forcibly stretch and rip open the multiple small wound tracks produced by the fragments. The resulting wound is similar to one produced by a commercial expanding bullet used for varmint hunting, however the maximum tissue damage produced by the military bullet is located at a greater penetration depth.
(The increased wounding effects produced by bullet fragmentation were not well understood until the mid-1980’s. Therefore the wounding effects of the original M16 rifle bullet were not an intentional U.S. military design characteristic.)
At distances between 100-200 yards the bullet commonly breaks in half at the cannelure forming two large penetrating fragments, the nose and base.
At distances beyond 200 yards the bullet usually remains intact due to velocity decay. It simply yaws 180 degrees to penetrate backwards through the body.
Both the M193 and M855 bullets demonstrate similar terminal performance as described above, when fired from rifles fitted with a 20-inch or longer barrel.
Shooting the M193 or M855 from a rifle with a barrel length less than 14.5-inches produces insufficient muzzle velocity to achieve the terminal performance described above. A rifle fitted with a 14.5-inch barrel is adequate for close-quarters battle. For engagements anticipated at greater than room distance but less than 100 yards, a rifle fitted with a 16.5-inch barrel should be employed to ensure sufficient velocity.
The older 55-grain M193 (M16A1) cartridge is not sensitive to rifling twist rate and can be fired in rifles with 1:12, 1:9 and 1:7 rates of twist. However, the newer M855 (M16A2) cartridge is best used with a rifling twist rate of 1:7 or 1:9. When the M855 is fired in a rifle with a slower rate of twist the longer 62-grain bullet can yaw up to 70 degrees in free trajectory through the air, substantially degrading accuracy.
The wound ballistics of the U.S. military Olin M193/Winchester 55 grain FMJ (X223R1 or Q3131) and green tip U.S. military Olin M855/Winchester 62 grain FMJ (RA556M855) cartridges makes them an adequate choice for use against violent criminal offenders.
Additional testing has indicated that errant bullets (military FMJ and commercial .223 Remington JSP/JHP) which do not hit an attacker appear to penetrate fewer walls and other common building materials than stray handgun bullets.
http://www.firearmstactical.com/briefs13.htm
It would be more accurate to say that the modern, ultra-accurate AR-15's have a "free floating handguard" -- the barrel was never supported by the handguard, as we'd think of in a conventional stock in a conventional rifle (OK, let's use the M-14/M-1A as an example). The handguard was the mounting point for the sling on the M-16/AR-15, and when using said rifle with a sling in proper rifleman form, the sling is pulling the barrel off-center, since the only other point of support for the barrel is the receiver.
The issue of the handguard/barrel interaction is yet another problem with the M-16/M-4/AR-15.
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