.338 Lapua Magnum
The .338 Lapua Magnum (8.6 x 70 mm or 8.58 x 70 mm) is a specialized rimless bottlenecked centerfire cartridge developed for military long-range sniper rifles. The Afghanistan War and Iraq War made it a combat-proven round with ready and substantial ammunition availability. The .338 Lapua is a dual-purpose anti-personnel and anti-material round; however, its anti-material potential is limited, due to the bullet's lower kinetic energy compared with that of the .50 BMG's 35.64 to 55.08 gram (550 to 850 grain) projectiles. The loaded cartridge is 14.93 mm (0.5878 in) in diameter (rim) and 93.5 mm long. It can penetrate better-than-standard military body armour at ranges up to 1000 meters and has a maximum effective range of about 1750 meters. Muzzle velocity is dependent on load and powder temperature and varies from 880 to 915 m/s (2887 to 3002 ft/s) for commercial loads with 16.2 gram (250 grain) bullets, which results in about 6525 Joule (4813 ft•lbf) of muzzle energy. In addition to its military role, it is increasingly used by big-game hunters and civilian long-range shooting enthusiasts. The .338 Lapua Magnum is suitable for hunting any game animal on the planet, though certain sub-Saharan Africa countries have a 9.53 mm (.375 in) minimum calibre rule for hunting Big Five game - i.e. leopard, lion, cape buffalo, rhinoceros and elephant. It also cannot be used in countries which ban civil use of former or current military rifle cartridges.
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History
In 1983, Research Armament Co. in the USA began development of a new, long-range sniper cartridge capable of firing a 16.2 gram (250 gr), .338-inch diameter bullet at 914 m/s (3000 ft/s). After preliminary experiments, a .416 Rigby case necked down to take a .338-inch bullet was selected, since this diameter presents an optimum of sectional density and penetrating capability for practical spin stabilized rifle bullets (bullets up to about 5 to 5.5 calibres in length)[1]. The .416 Rigby is an English big game cartridge that was designed to accommodate 325 MPa (47137 psi) pressures. One of the disadvantages to these old cartridge cases intended for firing cordite charges instead of modern smokeless powder is the thickness of the sidewall just forward of the web. During ignition, the cartridge's base, forward to the bolt face, is not supported. The case is driven back against the bolt face which results in the stretching of the case, particularly the sidewall immediately forward of the web. When the sidewall resists the outward expansion against the chamber, the pressure stretches the case thereby increasing its length resulting in the sidewall becoming thinner at that stretch point. Brass Extrusion Labs Ltd. (B.E.L.L.) of Bensenville, Illinois, made the cases, Hornady produced bullets, and Research Armament built the rifle under contract for the U.S. Navy. Subsequently, Lapua of Finland put this calibre into production.[2] The program was later cancelled when they were unable to make it meet the project's velocity target 16.2 gram at 914 m/s (250 gr at 3000 ft/s), due to weak brass cases.
From American origins, the current .338 Lapua Magnum cartridge was developed as a joint venture between the rifle building company Accuracy International and ammunition manufacturer Lapua (Malcolm Cooper, personal communication with the deceased founder of Accuracy International). In the .338 Lapua Magnum cartridge case design, particular attention was directed toward thickening and metallurgically strengthening the case's web and sidewall immediately forward of the web. In modern solidhead cases, the hardness of the brass is the major factor that determines a case's pressure limit before undergoing plastic deformation. Lapua tackled this problem by creating a hardness distribution ranging from the head and web (hard) to the mouth (soft) as well as a strengthened (thicker) case web and sidewall immediately forward of the web. This resulted in a very pressure resistant case, allowing it to operate at high pressure and come within 15 m/s (50 ft/s) of the original velocity goal. Lapua also designed a projectile modelled after its .30 calibre Lock Base bullet configuration. The result was the .338 Lapua Magnum cartridge which was registered with CIP (Commission Internationale Permanente Pour L'Epreuve Des Armes A Feu Portative) in 1989. With the procurement by the Dutch Army, the cartridge became NATO codified.
The .338 Lapua Magnum is considered an ideal military long-range anti-personnel cartridge by long-range sniping specialists like John D. Taylor and Dean Michaelis. It fills the gap between weapons chambered for standard military rounds such as the 7.62 × 51 mm NATO and large, weighty rifles firing the .50 BMG cartridge. It also offers a tolerable amount of barrel wear, which is important to military snipers who tend to fire thousands of rounds in practice every year to acquire and maintain expert long-range marksmanship.[3] In terms of performance and delivered energy the .338 Lapua Magnum falls between the .50 BMG and 7.62 mm NATO. Good factory loads, multiple projectile weights and factory special application ammunition for the .338 Lapua Magnum are all available.
Due to its growing civilian popularity, several high quality tactical and match (semi) custom bolt actions designed for the .338 Lapua Magnum are becoming available. These (semi) custom bolt actions are used with other high grade rifle and sighting components to build custom sporting and target rifles. Such rifles are ordered by long-range accuracy orientated shooters and built by specialized, highly skilled gunsmiths and can cost thousands of dollars. When built to expectation such rifles are very accurate - 0.5 MOA or better consistent accuracy for a particular rifle with optimized ammunition is considered normal. Only expert marksmen can make use of this extreme accuracy potential.
Law enforcement and military users
The .338 Lapua Magnum cartridge is in law enforcement or military [4] use with:
Albania - RENEA - Sako TRG-42
Australia
Belgium - Accuracy International AWSM
Canada - Canadian Forces - PGWDTI Timberwolf Tactical
Denmark - Sako TRG-42
Finland - Finnish Defense Forces - 8.6 TKIV 2000 = Sako TRG-42
Estonia - Military of Estonia - Sako TRG-42
Germany - Erma SR-100, AMP Technical Services DSR-1
Indonesia - Kopassus - Accuracy International AWSM
Ireland
Italy - Sako TRG-42
Netherlands - Dutch military - Accuracy International AWSM
Singapore - PGM Mini-Hecate .338
Slovenia - Military of Slovenia - PGM Mini-Hecate .338
Spain - Sako TRG-42
Switzerland - Sako TRG-42
Turkey
United Kingdom - British military - Accuracy International AWSM
United States - some US Military units - Remington M24A3 SWS
The Accuracy International AWSM rifle chambered in .338 Lapua Magnum is currently (2007) in service with the British Army and Royal Marines in Afghanistan and Iraq.
The .338 Lapua Magnum has been designated a "cartridge of interest" by the National Defense Industrial Association (NDIA). It is being groomed to replace the .300 Winchester Magnum and the .50 BMG for anti-personnel long-range service in the US Military.[citation needed]
Cartridge dimensions
Extremely thick-walled brass results in a 7.402 ml (114.0 grains) H2O cartridge case capacity for the .338 Lapua Magnum. The exterior shape of the case was designed to promote reliable feeding and extraction in bolt action rifles and machine guns alike, under extreme conditions.
.338 Lapua Magnum maximum cartridge dimensions. All sizes in millimetres (mm). Americans would define the shoulder angle at alpha/2 ≈ 20 degrees. The common rifling twist rate for this cartridge is 254 mm (1 in 10 in), 6 grooves, Ø lands = 8.38 mm, Ø grooves = 8.58 mm and the primer type is large rifle magnum.
According to the official CIP guidelines the .338 Lapua Magnum case can handle up to 420 MPa (60,915 psi) piezo pressure. In CIP regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum CIP pressure to certify for sale to consumers.
The American .338-378 Weatherby Magnum cartridge introduced in 1998 is probably the closest currently (2007) commercially available ballistic twin of the .338 Lapua Magnum. The .338-378 Weatherby Magnum is however a belted cartridge.
Ballistic performance of the .338 Lapua Magnum
For a typical .338 Lapua Magnum military sniper rifle like the Sako TRG-42 with a 690 mm (27.17 inch) long 1 in 12 inch rifling twist rate barrel at sea level, 1500 meters (1647 yards) is considered to be the maximum shooting distance for man sized targets when using standard Lapua military loads. The 16.2 gram (250 gr) Lapua Scenar bullet (G1 BC = 0.675), for which the TRG-42 was optimized, has a supersonic range of 1500 meters under warm summer conditions at a muzzle velocity of 915 m/s (3002 ft/s). However, to be able to maintain over 90% hit probability on non-moving targets, this maximum shooting distance has to be reduced to 1300 meters (1422 yards) at freezing point conditions or 1100 meters (1312 yards) in arctic winter conditions, when the muzzle velocity may drop to 880 m/s (2887 ft/s). Only during optimal warm summer conditions (muzzle velocity increases up to 915 m/s (3002 ft/s)) is the maximum shooting distance of 1500 meters (1647 yards) is realistically achievable.
Loaded with more aerodynamic .338 calibre bullets than the ones Lapua uses such as the Sierra Match King .338 19.44 gram (300 gr) bullet (G1 BC ≈ 0.768) or the Lost River Ballistics J40 .338 17.5 gram (270 gr) CNC manufactured mono-metal bullet (G1 BC = 0.871) the long-range performance and maximum range of .338 Lapua Magnum rifles can be extended. These longer Very Low Drag bullets require a 1 in 10 inch twist rate to stabilize them. The .338 17.5 gram Lost River Ballistic Technologies J40 match bullet (G1 BC = 0.871) is one of the most aerodynamic .338 calibre bullets available. It has a 1829 meters (2000 yards) supersonic range under optimal warm summer conditions at a muzzle velocity of 869 m/s (2850 ft/s). This makes engaging static targets up to 1800 meters (1969 yards) feasible.
Improvement beyond this standard while still using standard .338 Lapua Magnum brass is possible, but the bullets have to be very long and the normal cartridge overall length of 93.5 mm has to be exceeded. The common 1:10 inch rifling twist rate also has to be tightened to stabilize very long projectiles. Such commercially non-existent cartridges are termed "wildcats". The use of a wildcat .338 Lapua Magnum based cartridge demands the use of a custom or customized rifle with an appropriately cut chamber and a fast-twist bore. An example of such a special .338 calibre extreme range bullet is the German CNC manufactured mono-metal 18.92 gram (292 gr) LM-105 (G1 BC ≈ 1.133 – this Ballistic coefficient (BC) is calculated by its designer, Mr. Lutz Möller, and not proven by Doppler radar measurements). The LM-105 bullet has an overall length of 54.79 mm (2.157 in) and derives its exceptional low drag from a radical LD Haack or Sears-Haack profile in the bullet's nose area . Rifles chambered for this wildcat cartridge, with a cartridge overall length of 105 mm (4.13 in), and equipped with custom made 1:7 inch progressive twist rate[5] 900 mm (35.43 in) long barrels finished first and second at several long range competitions. It’s most recent win (2007) in an international Special Forces and police sniper competition in Switzerland was against rifles chambered for .308 Winchester up to .50 BMG at ranges from 100 m – 1500 m (109 yd – 1640 yd). The LM-105 bullet exhibited its very low wind drift susceptibility notably at ranges beyond 800 m (875 yd)[6].
.338 Lapua Magnum as a parent case
The .300 Lapua Magnum
The commercially successful .338 Lapua Magnum cartridge has functioned as the parent case for the .300 Lapua Magnum, which is essentially a necked-down version of the .338 Lapua Magnum. The .338 cartridge case was used for this since it has the capability to operate with high chamber pressures which, combined with smaller and hence lighter bullets result in very high muzzle velocities.
The Finnish ammunition manufacturer Lapua got the .300 Lapua Magnum CIP certified, so it became an officially registered and sanctioned member of the Finnish "family" of super magnum rifle cartridges. The .300 Lapua Magnum is not commercially available and currently exists only as a CIP datasheet. It is however still used by a few shooters who produce the cases from .338 Lapua Magnum brass by reshaping the shoulder and neck, and handloading it with .30 calibre bullets.
The .300 Lapua Magnum has a 7.337 ml (113.0 grains) H2O cartridge case capacity. The exterior shape of the Lapua Magnum case was designed to promote reliable feeding and extraction in bolt action rifles and machine guns alike, under extreme conditions.
.300 Lapua Magnum maximum cartridge dimensions. All sizes in millimetres (mm). Americans would define the shoulder angle at alpha/2 ≈ 25 degrees. The common rifling twist rate for this cartridge is 240 mm (1 in 9.45 in), 4 grooves, Ø lands = 7.62 mm, Ø grooves = 7.82 mm and the primer type is large rifle magnum.
According to the official CIP guidelines the .300 Lapua Magnum case can handle up to 470 MPa (68,167 psi) piezo pressure. In CIP regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum CIP pressure to certify for sale to consumers.
This for rifles very high maximum allowed chamber pressure level indicates that the cases of the .300 and .338 Lapua Magnum are built extremely sturdy to cope with this for rifles very high operating pressure. The large boltface combined with the high 470 MPa maximum pressure makes that the .300 Lapua Magnum should only be chambered in rifles that are capable of handling such large and fierce cartridges and thus high bolt thrust safely. Chambering such powerful super magnum cartridges in rifles intended for normal magnum rifle cartridges and using 470 MPa loads can cause serious or fatal injury to the shooter and bystanders.
Wildcats
The .338 Lapua Magnum case is also used as the parent case for a host of modified variants that neither are officially registered with and sanctioned by CIP nor its American equivalent, SAAMI. Such cartridges which use commercial factory cases are generally know as wildcats. By blowing out standard factory cases the wildcatter generally hopes to gain extra muzzle velocity by increasing the case capacity of the factory parent cartridge case by a few percent. Practically there can be some muzzle velocity gained by this method, but the measured results between parent cartridges and their 'improved' wildcat offspring are often marginal. Besides changing the shape and internal volume of the parent cartridge case, wildcatters also can change the original calibre. A reason to change the original calibre can be to comply with a minimal permitted calibre or bullet weight for the legal hunting of certain species of game. Because the .338 Lapua offers a large and exceptionally sturdy, pressure resistant cartridge case that can be relatively easily reloaded and hence be reused several times it has become quite popular amongst wildcatters. With the .338 Lapua Magnum as the parent case wildcatters have created 7 mm (7 mm Katzmeier), .30 (.30-338 Lapua (Triebel), .30 Wolf), 8 mm (8 mm-338 Lapua (Triebel), LM-101), .338 (.338 Yogi, LM-105), 9.3 mm (9,3-338 Lapua Magnum (Triebel)) and .375 calibre variants.
See also
External Links and Sources
- Lapua official site
- Lapua Rifles
- Lapua product brochure .338 Lapua Magnum ammunition
- Modern Firearms List of Sniper Rifles
- Lutz Möller's .338 Lapua Magnum Page
- PGWDTI Timberwolf Tactical rifle (.338 Lapua Magnum and .408 Chey Tac chamberings)
- QuickLOAD internal ballistics predictor computer program for fire arms
- The .338 Lapua Magnum Cartridge: Part 1 - Origin, Development and Future
- The .338 Lapua Magnum Cartridge: Part 2 - The Men Behind the Cartridge
- Reloader's Nest, a resource for all handloaders seeking the ultimate load.
- LM-101 Long Range Bullet for a 8 mm - .338 Lapua Magnum High Performance Wildcat Cartridge
- LM-105 Long Range Bullet for the .338 Lapua Magnum
- ^ What is the Maximum Length of a spinstabilized Projectile? by Mr. Beat Kneubühl
- ^ Cartridges of the World, 8th edition
- ^ The Finnish Army found out during a test/trails program and 7 years of actual service that the barrels of their Sako TRG-42 sniper rifles lasted 7000 to 8000 rounds with Lapua Lock Base B408 factory ammunition before showing impermissible accuracy decay. The Finnish Army consistent accuracy requirement for these rifles is ≤ 1 MOA at 1000 m. If this requirement is not met the TRG-42 gets a new barrel. The continuous use of very powerful handloads (which results in higher muzzle velocities) resulted in much quicker throat erosion reducing the TRG-42 barrels accuracy life to 1500 to 2000 rounds.
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| New for 2006 is the Model M24A3 Sniper Weapons System – a long range version of the widely used Model M24 Sniper Weapons System which has been the standard for the US Army since 1988. Chambered in the highly successful 338 Lapua Magnum, the M24A3 is yet another evolution of the M24 Sniper Weapons System. Known for its extreme long range accuracy the 338 Lapua Magnum is quickly becoming the obvious selection for our nations warriors. Features of the newly introduced Model M24A3 Sniper Weapons System include a highly effective external extractor; offered by custom gun shops for decades. The M24A3 also features a detachable 10-round box magazine, H&S Precision Pro-2000 stock assembly OR the Accuracy International Chassis System (AICS®), both feature adjustable length of pull (LOP) and an adjustable cheek rest. Additionally the M24A3 features the Modular Accessory Rail System, a Leupold Mark 4™ 8.5-25X M1, and an OPS INC® 12th Model 338 LM Muzzle Break and Sound Suppressor. The Model M24A3 Sniper Weapons System is based upon the combat proven M24 Sniper Weapons system in use today by the US Army in the Global War On Terrorism (GWOT) and is widely considered as the standard by which other sniper rifles are judged. The Model M24A3 Sniper Weapons System will continue to offer surgical precision and reliability to those who demand the best.
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