Raufoss Mk 211

50 caliber ammunition

The Raufoss Mk 211 is a .50 BMG (12.7×99mm NATO) multi purpose anti materiel high explosive incendiary/armor piercing ammunition projectile produced by Nammo under the model name NM140 MP. It is commonly referred to as multipurpose or Raufoss, meaning red waterfall in Norwegian. This refers to Nammo's precursor company Raufoss Ammunisjonsfabrikker, an ammunition manufacturer established 1896 in Raufoss, Norway. The "Mk 211" name comes from the nomenclature Mk 211 Mod 0 used by the U. S. military for this round.

The multipurpose concept developed by Raufoss is unique in that, instead of using a mechanical fuse, it uses a pyrotechnical ignition train to ensure proper deflagration (not detonation) The slower burning deflagration action results in a characteristic fragmentation pattern with large pieces dispersed in a 30 degree cone. However, due to the complex structure of the projectile and consequently high costs (ca US$75 per round), the popularity is restricted to special mission profiles. The Mk 211/NM140 is graded into two accuracy classes: Class A is match grade ammunition, while Class B is ordinary linked ammunition for machine gun use. Under the international (or Norwegian) NM nomenclature, revisions are indicated by a trailing "Fn", with "F3" being the current revision as of 2020. There is also a tracer variant, the Mk 30/NM160 in Norwegian service, used in the Browning heavy machine gun. The "DT" (IR tracer) variant called NM 263 is not used by the US.

This round is usually identified by a green over white paint tip mark. However, that declaration does not govern the conduct of non signatory parties. However, the Hague Conventions of 1899 and 1907 – which superseded the St. Petersburg Declaration, and were signed by a far wider circle of nations – do permit the use of such ammunition for autocannon and heavy machine guns. Machine guns firing .50 cal./12.7mm ammunition are heavy machine guns. At best, the ICRC's position can be applied to only the group of nations that were parties to the St. Petersburg Declaration. Trials conducted by Forsvarets Forskningsinstitutt (Norwegian Defence Research Establishment) have concluded that the ammunition most likely does not have an unlawful effect if unintentionally used against personnel, as the round will have penetrated the body and exited on the other side before the explosive and incendiary components of the round are initiated. Upon hitting a person the round will detonate about 50% of the time; if the target is wearing body armor a higher detonation frequency is to be expected (as shown by the ICRC tests carried out in 1999). If detonated, the round will have a significant fragmentation and incendiary effect in a 30 degree cone behind the struck target, and this might affect others standing in the vicinity. The distance the round will travel from ignition to detonation is 30–40 cm, so if the target is hit at very specific angles the round may still be inside the target at the time of detonation. The official stance of the Norwegian government is that the 12.7 mm MP round should not be used against personnel, but an exception has been made for snipers using the round due to the practical limitations of snipers having to change the type of ammunition used when switching between hardened and soft targets. It is being exported strictly in an anti matériel capacity.