Terminal Effect Ammo

  When I was offered the assignment of writing this…


When I was offered the assignment of writing this article, I saw a great opportunity to clarify a lot of misconceptions and myths that have surrounded the MK211. Many armies field the Nammo Multi-Purpose (MP) ammunition in various denominations, such as MK211 or NM140. This is due to the ammunition being assembled with various components at various locations, but always with the same Nammo bullet, manufactured at their factory at Raufoss, Norway.

In this article I will outline the general performance and specifications of the MP round without giving precise data about its maximum capabilities. With the U.S. military and allies in Harm’s Way, I have decided not to give away those data that would fully describe the MP round effects and could help our enemies. The Multi-Purpose ammunition was born in the late 70´s when the Norwegian Army Material Command demanded thenew requirements for the 12.7mm weapon family. The requirements included increased kill probability, accuracy, portability of the weapon in the field and improved mean point of impact on target.

Until then, the 12.7mm had been “just” medium calibre round. It packed a lot of punch and it was the biggest rifle caliber available, but it was nothing more than a kinetic energy round. The 650gr+ bullet had API and AP capability with or without tracer compound, and in the most common configuration—the M33 ball—it was just a big bullet with a lot of energy. The requirements filed by the Norwegian Army and the development of the MP concept gave the “fifty” a new life and has converted it into the undisputed king of the infantry arsenal.

This set of requirements was supposed to increase the 12.7mm weapon system from an effect level just above 7.62mm to one closer to that of a 20mm cannon. The answer to these requirements was the 12.7mm Nammo Multi-Purpose cartridge and the Barrett M82 rifle.

Based on the principles from the 20mm NM75 developed 10 years earlier, the load had similar terminal by delivering fragments, blast and incendiary effect after penetrating light targets. It was optimized for an anti-vehicle role with a secondary role against light armor and area suppression. That “area suppression effect” is the one that has induced most erroneous perceptions about the MP bullet, helped by various combat videos, in which the fragmentation cone effect of the MP round is described.

The 12.7mm multipurpose concept was introduced in 1981 with a design focused on penetration, fragmentation, incendiary and blast effect.

In the photo above, we can see the jacket covering the projectile. In the front we have the incendiary RS41; we have the steel shell body containing the high explosive, incendiary and tungsten carbide penetrator. The projectile contains no fuse or sensitive high explosives (primary explosives).

Now you know what’s inside a MK211 bullet, but how does it work? Chronologically, the MP will penetrate, delay, function, fragment, blast and incendiary effect, until beyond 25 cm in the back of the target. We will have approximately 40 fragments of which 20 of them are effective and also incendiary compound fragments for more than 10m.

The incendiary effect is the first one we analyzed. We could see x-ray flash photos of a 12.7mm projectile in flight before and after hitting a 2mm dural plate. We could see that the deformation of the jacket was in the area of 3mm, which is necessary to ignite the incendiary. When fired against a 2mm dural plate at 200m, the projectile shall produce an incendiary flash, according to the NATO requirement, within 60cm behind target plate.

The MK211 will fail to ignite thin metal jerry cans. If the target is not capable of deforming the nose of the bullet and igniting the incendiary and effectively, you will only have a ball bullet.

To illustrate the fragmentation effect and pattern, ammunition makers often use a sandwich target. The MP projectile produces about 20 fragments and delivers them in a 25–30 degree cone inside the target. These fragments have the energy to penetrate a 1.25mm steel plate 2 meters behind the impact plate. The fragments will have an increase in velocity of about 10–15 percent, due to the blast pressure.

The projectile will ignite after hitting a 2mm dural plate in angles of impact between 0 to 85 degrees NATO. In angles between 45 and 85 degrees the projectile will ignite dural plates with thickness down to 1mm. When firing at the ground the projectile will ignite if the soil is reasonably compact. At short range, the projectile will function after impact in most kinds of soil, and this application of fragmentation when hitting a hard surface or the soil leads to the MP effect that has attracted most attention in the past years, mostly due to the videos that have appeared on the web.

The suppression effect is significant for the MP rounds compared to API rounds. Blast, flash, projectile fragments and debris from the ground are delivered in the target area. When hitting in the front of targets, the hit probability will be several meters behind the point of impact due to the fragmentation cone. The suppression effect from the MP rounds is significant and deadly. There are numerous combat reports and combat videos that demonstrate the use of M107/MK211 against barricaded insurgents. The damage to the barriers and the targets are severe and bears witness to the effectiveness of the MP suppression capability.

The probability of being hit by lethal fragments is quite high several meters behind the point of impact and when we take in consideration that the fragments will spread out in a cone we can see that it covers a quite large area, see photo below. In a comparison with an API projectile we see that the MP projectile provides a much higher probability of hit.

Due to the tungsten carbide penetrator, the MP projectile has a considerable penetration capability. It is nearly as effective as the best AP rounds, plus delivers the MP effect which greatly increases its terminal ballistics. The penetrator has a weight of 14 grams and is designed to have the best possible penetration capability in oblique angle targets.

mk2.jpgIn the heavy-armor bullet hole we can observe what happens when the projectile hits the armor plate. The jacket and steel shell body are stripped off the penetrator, which continues into and through the armor. In this kind of target nearly all of the blast, fragmentation and incendiary effect stays in front of the target. The penetrator goes through the armor
without eroding.

When confronted with heavy armor such as hardened steel of more than an inch, the effect is as follows: The jacket and shell body material has melted together with and into the armor and form a ring round the hole from the penetrator. The diameter of the hole is the same as the penetrator itself, 7mm.

The penetrator will, in most cases, break up in the moment it passes the armor, and together with fragments from the armor itself, give significant post armor effect. The velocity on these fragments behind a 22mm armor plate at a distance of 100 meters will be between 200 and 400 meters per second, and some of the fragments have the energy to penetrate a 1,5mm steel plate. This means that after the tungsten carbide penetrator passes though the barrier, you still have several supersonic fragments capable of considerable ricochet if going into enclosed areas.

One of the most widespread myths about the MK211 is that it can ignite if hit with force or if subjected to a great shock such as being in a vehicle blasted by an IED. The rounds are operational in any of nature’s MET conditions, around +/- 55°C, and will survive even more extreme temperatures. The rounds are safe against: Dropping, rough handling, vibration, temperature, shocks, electronic pulsing and long storage. As an example of the safety of the rounds in standard Browning M2 heavy barrels, 300 rounds may be fired in one burst without giving a cook-off of the projectile if the last round remains in the barrel.

After drop-testing, these rounds and projectiles are safe to handle; they can be fired and will function against heavier targets. Due to damage in the nose, they are less sensitive to thin target plates like 2mm dural and the reduction in the ballistic coefficient will affect the trajectory, too.

When we talk about any ammunition and its use on a sniper rifle or on a SASR, one of the most important features of a rifle round is accuracy. The MP NM140 round has excelled in accuracy, exhibiting a mean radius of 40 – 70 mm at 550m with most of the lots around 55mm. This translates around 1 MOA if we rate the round with civilian specs, which is fairly good when considering all the other specs the bullet has to comply with.

Nammo has decided to certify lower accuracy performances on its MP rounds. They should rate the ammo with the accuracy that it is capable of achieving. Assembly of ammunition outside the Raufoss factory makes may effect some quality, but I still think that the NM140—and on the same line the U.S. made MK-211—should be rated around 100mm MR. The ammunition assembled in the U.S. has demonstrated to be up to these specs and with the MK-211 you can expect around 1.5 MOA accuracy out of the box.

When compared to the API round, the MP exhibits an effectiveness factor more than three times better. The probability of incapacitation (PK) is 2.8 : 1 and the probability of hit (PH) is > 5 : 1. In regards to target incapacitation and enemy suppression, there is no contender to the Nammo MK-211 and NM140.

There are some times in which the explosive or incendiary effect makes the use of the MK211 inapplicable. Be it for the possible collateral damage to civilians or simply because of possible range fires, the use of MK211 during summer sniper practice is not possible in many regions. For example, in Spain, due to environmental concerns, the use of incendiary or explosive ammo is forbidden during the dry summer months.

Nammo recognized this situation and started a program to offer the MK-211 users an inert bullet option with the same external ballistics of the MP round. All snipers know that the M33 has a different trajectory and also different group spread characteristics, which make the range practice during those summer months very frustrating.

After years of R&D, the new Nammo 12,7mm (.50 cal) Special Grade (SG) Ammunition (snipers call it Sniper Grade) is here. The design objective for this type of ammunition is to obtain long-range accuracy from Anti Material Rifles (AMR) with the same inner and outer ballistics as MK-211 (NM140) MP, MP-T & AP-S. SG ammunition will replace Standard Ball M33 and M17 that exhibit a much larger dispersion.  SG ammo is the corporate name for the ammo, but most snipers call it Sniper Grade. It has the same basic form and dimensions as MK-211. It is lead-free, has an inert filling for support, and the weight is 45 grams (651 grains), the same as the MK-211. The Special Grade Tracer (SG-T) has a bullet with a tracer element and the same tracer requirements as the MP-T. Qualified according to all relevant paragraphs in STANAG 4383 by FMV Sweden, it is in use by Swedish and Spanish forces, while Norwegians, Germans and some other NATO countries are in process of qualification. I have personally run the qualification tests for the Spanish Army, and in them the new SG ammo demonstrated to be the most accurate commercial ammo ever tested by this author and by the Army, too. It passed the comparison with the IMI M33 and even with the NM140 with flying colors, and it exhibited an accuracy improvement over the M33, in every one of the 21 ten-shot groups fired. In some, the difference was so great that we could hardly believe it. The same tendency was obtained with both the new M95SP and two Accuracy International (AI) AW50s used for testing the ammo in two different platforms. In those tests, the M95SP outperformed the AI in accuracy and also in every other aspect, except ergonomy. The AI proved to be a very capable rifle, having the adjustability of a target rifle, but hindered by excessive weight and size.

In the same upscale, match-quality, ammunition line as the SG, Nammo is studying the market feasibility of new .50-caliber products that will offer true 2000m+ supersonic capability and sub-MOA precision but on a completely new design that does not need to follow the MK-211 trajectory. Hopefully Nammo will decide to market it. This will be a dream come true for the extreme range snipers. I truly believe that no NATO 12.7mm rifle should be without its MK-211 ammo and with Nammo SG ball, for practice and counterpersonnel use.

Load Comments
  • eduardo abril de fontcuberta

    The NM140 (MK211) MP round will not work in loose sand or soil. You are completely right, all you can get is an unreliable effect or ricochet, if it hits a big rock.

  • In regards to your article on the Mk211. One of the biggest stories floating around, which I don’t personally believe, is that the round would have lethal effects when fired at troops in the open on loose terrain i.e. sand, dirt… I just can’t see the frag radius having an effect on troops in the open. At best you might get one or two frags to randomly ricochet off of a rock and get the Golden BB to take out one guy. I fully understand and promote the effects when the round is used in its intended capacity, firing through light armor and having the frags affect those soft squishys inside the hull. But I just dot see how it could do anything other than make an impressive hole in the ground when fires at a 45 degree angle into the earth. I have been told that it would have a 20 meter lethal ring when impacting near at troops in the open…I’m just not buying it. Tell me I’m wrong??

  • Augusto Abril

    ese “weapon authority”. Muy bien.