5.56 x 45 round has been upgraded (Mk 318 Mod 0)

Discussion in 'General Firearms Discussion' started by 1024Megabytes, Dec 27, 2014.

  1. Others may have heard of this information. The 5.56 x 45 round has been upgraded. The new round is now one of the types of ammunition being fielded used by the Marines and is called the Mark 318 Mod 0 (or Mk 318 Mod 0) round. It uses a 62 grain bullet with an open-tip design. They call it open tip match (OTM). It has been in the field since around late 2010.

    Out of a 14 inch barrel, the Mark 318 bullet has a muzzle velocity of around 2,925 feet per second. Increased velocity and decreased muzzle flash were accomplished by the type of gunpowder used.

    Initial studies showed that insurgents hit by it suffered larger exit wounds, although information was limited. Special Operations Science and Technology rounds were used alongside M855 rounds in situations where the new round would be more effective. In July 2010, the Marines purchased a lot of this ammunition.

    Finally something better than the older M855 5.56 x 45 62 grain round. The United States Army was not interested in the Mark 318 Mod 0 ammunition.

    The Marines are also now using an open tip ammunition design with the 7.62 x 51 round along with the older 7.62 full metal jacket ammo. The new round is called the Mark 319 Mod 0.

    See more information here:

    [ame]https://www.youtube.com/watch?v=pZlOOIDpHv0[/ame]
     
  2. Johnny_B_Goode

    Johnny_B_Goode Member

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    Target shooters have used non expanding hollow point boat tail bullets for quite a while. At rifle velocities the hollow point creates a ballistic bubble that makes the bullet more aerodynamic.

    I am not sure more velocity is a good thing for the 5.56x45. Once velocity reaches a certain point penetration suffers, even with a FMJ bullet. There are hundreds of ballistic gelatin tests on YouTube. Once you reach a certain velocity friction prevents the bullet from penetrating.

    Here is one ballistic gel test I found. You will get more results from MK318 mod0
    [ame]https://www.youtube.com/watch?v=cRB0LwiNz24[/ame]

    The bullet does not expand as much as it fragments. It did give great penetration on bare gelatin. Barriers such as denim put a lot more stress on the bullet. The way the bullet fragmented it would have to prove itself on hard barriers such as plywood or sheet metal before I would use it for hunting or SD. Animal hide is tough to penetrate that is why I would want to see a barrier test.
     
    Last edited: Dec 27, 2014

  3. Think1st

    Think1st Supporting Member

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    That's a good thing. It means more kinetic energy transfer to the target instead of losing it all through the exit wound.

    Ond of the subjects that has repeatedly come up over the last decade and a half is that the 5.56x45 FMJ round was just zipping through targets, perforating them and not causing sufficient trauma to drop them, immediately, all the time.

    It's one of the reasons that the 6.8mm was developed--better stopping power. If this OTM bullet design does just as good of a job, then that's a good deal because it means improved lethality from the same caliber and no need to discuss fielding new rifles to accommodate them.
     
  4. Whoever made the United States Army logistics decision to bypass the Mark 318 Mod 0 ammunition was very unwise. The Army adopted the M-4 as its official rifle. With the shorter 14.5 inch barrels the M-4 is even less effective with the 5.56 x 45 round.

    I am still not a fan of the 5.56 x 45 round. It was too big a compromise on power when the M-16 rifle was issued. The round is less effective than most other rifle rounds.

    The .300 Blackout round with a 115 grain bullet is very effective out to 330 yards from a 16 inch barrel with no loss in magazine capacity. And that makes a better carbine than the M-4.
     
  5. Johnny_B_Goode

    Johnny_B_Goode Member

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    FMJ ammo is supposed to just rip right through a target. The US never signed the Geneva Convention treaty. I am not sure why our soldiers have been forced to abide by a treaty we never signed. The problem with a 5.56x45 is if we use soft points like hunting ammo penetration is less than many 9mm HP cartridges.

    Energy dump is a myth, snake oil or a reason to sell ineffective ammo. If there was enough kinetic energy in a bullet to have a energy dump it would knock you down when you shot it. What happens is the bullet only has so many foot pounds of energy when it leaves the barrel. This energy cannot be increased in any way once the bullet leaves the barrel.

    When a bullet passes through an object it creates friction, more expansion, more friction. Once expansion reaches a certain point friction prevents the bullet from dispersing it's energy efficiently. In turn, penetration suffers the bullet doesn't drive deep enough to damage vital organs and other tissues like the spine. You cannot have a one shot stop if the bullet does not drive deep enough to hit the central nervous system. So expansion must be controlled. All expansion does is allow the bullet to cut a wider path that increases it's chances of hitting something vital.

    An exit wound is your friend. One of the ways a bullet incapacitates is by blood loss. When the goblin is leaking from two holes he is going to lose blood a lot faster. In turn, he is not going to be able to keep attacking once his brain stops getting any oxygen.

    When you get into larger calibers like the 270win, 30/06 308 and so on you have hydrostatic shock. Hydrostatic shock is forcing the blood to move quickly in the opposite direction that it is supposed to be flowing. This allows the bullet to damage a lot more tissue.
     
  6. Rachgier

    Rachgier Administrator Staff Member

    That's partially true. Surface area affects energy transfer. 5lbs of pressure on a needle will pierce the skin where 5lbs of pressure on a trashcan lid will not. All projectiles will transfer some of their energy in to the target, and the more energy that can effectively be transferred to the target will alter the amount of potential damage.

    Also, the round was not designed to "rip right through a target." It was designed to enter a target at 2,500 ft/s to yaw and fragment creating larger wound cavities thus increasing the "one-shot stop" capabilities of the round. The issue was that with shorter barrels and longer ranges, the velocity was decreasing to a level that prevented it from fragmenting and allowed it to pass completely through the target with "minimal" damage.

    Hydrostatic shock is also not limited to blood flow, it has to do with the compression of all liquids, and the transfer of the shockwave causing an overpressure which alone can rupture tissue in the directly affected organs. The overpressure also has a referred effect from the rapid transfer of blood away from the point of impact, not necessarily in a flow reversal, as you mentioned. Those manifest in the form of hemorrhaging that occurs in areas of the body that aren't directly affected by the projectile.

    One of the main problems that occurs when discussing ballistics is the frequent use of terminology that is incorrectly applied to the situation, simply because there is no better way to describe it in a simple manner. Energy dump, knock-down power, stopping power, etc. Because of their frequent use in marketing tactics, they have become the go-to words.

    Your description of what is required to create a one-shot stop could be used as an example. One does not need to "hit" the CNS, it simply needs to create enough of a disruption as to cause it to malfunction (send it in to shock). The amount of disruption required to cause the shut down (shock) will vary per the individual target. I have personally witnessed a Marine take a round to his thigh and drop like a ton of bricks and I have seen one take multiple rounds to the chest and keep right on rolling like they were foam darts from a Nerf gun. Now I WILL agree with you that the only way to effectively cause a "lights-out" shot is to destroy the CNS. That's why they used to teach Marines to shoot for the "Fatal-T" and high center mass shots for obvious reasons.
     
    Last edited: Dec 27, 2014
  7. Johnny_B_Goode

    Johnny_B_Goode Member

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    It is human nature to fall when hit by a bullet. Usually there are more bullets coming. Some people do have the ability to take more punishment. If we all could take the same amount of punishment we wouldn't have champion boxers for example. No one gets in a boxing match with someone of equal abilities and does not get hit. At a certain skill level it comes down to the boxer that will not quit no matter how much damage he suffers. Look at Ali. Foreman beat Ali so badly he was never the same. Yet Ali kept fighting and ended up winning the fight on points. People that get shot are the same way.
     
  8. Rachgier

    Rachgier Administrator Staff Member

    No, he didn't fall, he went down like a ton of bricks. Out cold, needed smelling salts and some heavy handed sternum rubs to bring him back up. Through and through flesh wound to the outer thigh, barely deep enough to qualify as anything more than a graze. His body went in to instantaneous shock and shut down. He caught some SERIOUSLY flak for it back in the FOB before he evac'ed. Hell, people pass out from tattoos and piercings all the time.
     
  9. Think1st

    Think1st Supporting Member

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    Just as a minor point of clarification, we are signatories to Geneva Conventions I-IV. They don't address the kinds of munitions that we can use; rather, they address the designation and treatment of combatants, non-combatants, and protected categories of personnel.

    The types of munitions that we can or can't use are governed by the Hague Declaration. We do recognize its provisions, but we use some limited caveats.

    Going back to the 5.56 NATO penetration matter, though, many handgun rounds will penetrate through solid media more effectively than 5.56 rounds just because they weigh more and retain more mass upon impact. While that penetration might be great for reducing the effectiveness of cover, it does not necessarily make for enhanced lethality. In the end, a quick check of ballistics tables will show that .223 rounds have roughly triple the muzzle energy of 9mm rounds (just an eyeball average of all different loadings).

    Energy always transfers. The laws of physics mandate it. With a collision, the energy can transfer in the form of heat, elastic transfer (when a pool ball hits another, stops dead and causes the other to move), or non-elastic transfer (when something crushable hits something else crushable causing the two objects to stay connected and move together. Increased friction associated with higher velocity will interfere with the depth of bullet penetration, but the very sudden decrease in its velocity will be answered with a sudden increase in the velocity of the surrounding media, manifested in the form of hydrostatic shock (kind of a liquid version of a non-elastic collision) and a temporary crush cavity. That means more trauma happens.

    The OTM bullet will penetrate deep enough to hit vital organs. As far as expansion goes, expansion isn't a desired characteristic so as to increase the odds of hitting something vital via a wider path, it is a desirable characteristic because it facilitates transfer of kinetic energy and enhanced hydrostatic shock. It does also help create a broader wound channel through with the target can lose more blood. There is no magic one-shot-knock-down round out there, but the more trauma that a round can inflict, the higher the likelihood of reducing the target's capacity to continue remaining afoot.

    If a bullet zips through and through without damaging much on either side of the wound channel, the target will not likely fall immediately unless the bullet takes out critical parts of the muscular-skeletal structure, key connective tissues, or disrupts neurological pathways. A bullet that transfers more energy to surrounding tissues will better facilitate target collapse if one of those critical systems isn't hit directly.
     
  10. Branth

    Branth Member

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    Man, there's a LOT of good info posted here. Proud of y'all! :D

    Personally, I'm still a bit floored they managed to squeeze 2925 FPS out of a 14.5" barrel with a 62gr projectile. I was under the impression that was the kind of performance you could expect out of a 55gr bullet, and 5.56 is really sensitive to barrel length. This stuff must just go thermonuclear in terms of chamber pressure.
     
  11. 45Man

    45Man Member

    The XM4 was given a longer 14.5-inch barrel with the M16A2's 1:7 inch rifle twist, to use the heavier 62-grain M855 rounds.

    Had the opportunity to test my AA at 300 yds. The M193, 55gr was greatly affected by a 10mph cross wind. Barrel is 1:7 instead of traditional 1:9.

    I now use 55gr in the 1:7 & 62gr in the 1:9.
     
  12. Think1st

    Think1st Supporting Member

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    While the M4 barrel was reduced to 14.5 inches from the 20 inches of the M16A2's barrel, it definitely needed the heavier 62-grain bullet to make up for the loss in velocity that its shorter barrel imparted. The 1:7 twist stabilizes heavier bullets much better than the slower ones. Heavier bullets require faster twists. Lighter bullets require slower twists in order to prevent being spun too quickly.

    I was having some disappointing results shooting 55-grain bullets from the 1:7 16-inch barrel on my own AR and had concerns that perhaps it was over stabilizing those bullets, so I looked up a nice article from G&A to find out some general rules of thumb about pairing bullet weights and barrel twists. It is at the following link:

    http://www.gunsandammo.com/ammo/pair-barrel-twist-rates-ammo/

    After reading it, you might decide to try the 62-grain bullets in your 1:7 barrel. I actually ordered a 1000-round case of CBC 62-grain 5.56x45mm ammo from Target Sports because I wanted to better match my ammo and rifle.
     
  13. ajole

    ajole Supporting Member

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    Well, that ain't right.

    It just depends. Adrenaline and conditions can do a lot.
     
  14. lklawson

    lklawson Staff Member

    Correct.

    4 Ways to Stop an Opponent

    Peace favor your sword,
    Kirk
     
  15. ajole

    ajole Supporting Member

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    Some questions...

    Weight to the rear...how stable is the 318, and how accurate at range? I assume the boat tail partially helps with that.

    Isn't this a lot like what I understood about the AK 74 bullet with the hollow but enclosed tip? Designed to fold and tumble inside targets?

    How are they justifying its use? That looks like a JHP round, to me. Is it because there's no core being jacketed? Edit...well, there IS a lead core, according to what I'm reading.
     
    Last edited: Dec 30, 2014
  16. 45Man

    45Man Member

    I have tried the 62 gr in the 1:7 & it is a definite improvement at longer distances. Just got 500 rounds of Wolf for $130/shipped. Still have some Addcom (UAE) brass cased 62-gr.
     
  17. Branth

    Branth Member

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    They're justifying it because the hollow tip is a leftover from the manufacturing process, where the jacket starts at the base and is drawn towards the tip, which is opposite of the usual FMJ way. They're also justifying it because the ammo is designed for accuracy, and the open tip is more or less an accident along the way, so it's not "designed" to expand. Therefore, it's not against the Hague conventions.

    That's what they're telling people anyway. Frankly, I consider it ridiculous that we're not allowed hollowpoint or softpoint ammo. We can turn a guy into a pink mist with a rocket, or dump 100 rounds per SECOND into a guy with a minigun, but we can't shoot him with plain old hunting ammo? Really?
     
  18. Bull

    Bull Just a Man Supporting Member

    Lol..... Hadn't really thought about that much B..... 55gr 5.56 hollow point, or 750gr Amax .50 cal bullet.... Which would I rather be shot with....
     
  19. lklawson

    lklawson Staff Member

    Really. It was an artifact of the times which, like many attitudes of the militaries of the world, became codified and has failed to be changed as the world continues to evolve.

    In the run-ups to the first Hague Convention (1899), the British had been using expanding point (and sometimes fragmenting) ammunition, frequently mis-named "Dum Dum" bullets, because of their greater effectiveness in stopping. The French and Germans (and most of the rest of Europe from what I can tell) were utterly horrified at the use of Hunting Ammunition on people. It was downright "uncivilized." The politicians, of course, took full advantage of this to vilify the British every chance they got. There was lots of anti-British propaganda about how evil they were, particularly for using "Dum Dum" bullets. Notice that at this time "machine guns" were in their infancy ("Potato Diggers" anyone, anyone?), aerial warfare was still Science Fiction, and Mechanized Warfare consisted of Battleships inaccurately lobbing shells or locomotive trains delivering troops and cavalry. It was the era of Teddy Roosevelt's famous charge up San Juan Hill.

    During the debates in the first Hague Convention, the British argued against the banning of "dum dum" bullets saying, "men penetrated through and through several times by our latest pattern of small calibre projectiles, which make small clean holes, were nevertheless able to rush on and come to close quarters. Some means had to be found to stop them. The civilized soldier when shot recognizes that he is wounded and knows that the sooner he is attended to the sooner he will recover. He lies down on his stretcher and is taken off the field to his ambulance, where he is dressed or bandaged. Your fanatical barbarian, similarly wounded, continues to rush on, spear or sword in hand; and before you have the time to represent to him that his conduct is in flagrant violation of the understanding relative to the proper course for the wounded man to follow—he may have cut off your head".

    The argument, though quite logical, failed to overcome the propaganda and the British lost that point by a vote of 22-2. Only the Brits themselves and the U.S. voted against the banning of "dum dum" expanding point ammunition.

    Here's an interesting chain, by the way. The reason that the U.S. is using .45 caliber ammunition is a direct result of the Hague Convention of 1899. Yup. You'll recall that during the Philippine Insurrection of 1899, the U.S. service man complained that the current issue .38 caliber handguns were failing to stop Moro warriors and "traded up" to the .45, right? Notice the dates. Hague Convention of 1899. Philippine Insurrection of 1899. Well, the reason that the U.S. voted with the British against the banning of "dum dum" expanding point ammunition because we wanted to use them in the Philippines! When that was no longer an option, and we were forced to use solid, non-expanding bullets, we made the quite logical decision to just up the size of the bullet itself.

    So, all of you .45ACP fans... You're in love with the round because the French were scared of magic exploding bullets of death used by the British! mu-hahahahaha!

    Peace favor your sword,
    Kirk