. 338 Lapua Magnum The . 338 Lapua Magnum ( 8 . 6×70mm or 8 . 58×70mm ) is a specialized rimless bottlenecked centerfire cartridge developed for military long - range sniper rifle s . 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 - materiel round , but its anti - materiel potential is limited , due to the bullet ' s lower kinetic energy compared with that of the . 50 BMG ' s projectiles . The loaded cartridge is in diameter ( rim ) and long . It can penetrate better - than - standard military body armour at ranges up to and has a maximum effective range of about . Muzzle velocity is dependent on load and powder temperature and varies from for commercial loads with bullets , which results in about of muzzle energy . Non - C . I . P . conforming British military issue overpressure . 338 Lapua Magnum cartridges with a overall length , loaded with LockBase B408 very - low - drag bullet s were used in November 2009 by British sniper Corporal of Horse ( CoH ) Craig Harrison to establish a new record for the longest confirmed sniper kill in combat , at a range of . In addition to its military role , it is increasingly used by hunter s and civilian long - range shooting enthusiasts . The . 338 Lapua Magnum is capable of taking down any game animal , though its suitability for some dangerous game ( Cape buffalo , hippopotamus , white rhinoceros and elephant ) is arguable , unless accompanied by a larger " backup " caliber : " There is a huge difference between calibers that will kill an elephant and those that can be relied upon to stop one . " History . Initial development . In 1983 , Research Armament Industries ( RAI ) in the United States began development of a new , long - range sniper cartridge capable of firing a , diameter bullet at that could penetrate five layers of military body armour at and still make the kill . After preliminary experiments , a . 416 Rigby case necked down to take a 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 calibers in length ) . The . 416 Rigby is an English big game cartridge that was designed to accommodate 325 MPa ( 47 , 137 psi ) pressures . One of the disadvantages of these old cartridge cases , which were 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 . During the process RAI employed Brass Extrusion Labs Ltd . ( BELL ) of Bensenville , Illinois , to make the . 338 / 416 or 8 . 58×71mm cartridge cases , Hornady produced bullets , and RAI built a sniper rifle under contract for the U . S . Navy . RAI found that the BELL cases did not fulfill the requirements . Pressed by military deadlines RAI looked for another case producer and contacted Lapua of Finland in 1984 . RAI was forced to drop out of the program due to financial difficulties . Subsequently , Lapua of Finland put this cartridge into limited production . The . 338 / 416 rifle program was later cancelled when the contractors were unable to make the cartridge meet the project ' s velocity target 16 . 2 gram at 914 m / s ( 250 gr at 3000 ft / s ) , due to weak brass cases . Final development . The current . 338 Lapua Magnum cartridge was developed as a joint venture between the Finnish rifle manufacturer SAKO and the British rifle manufacturer Accuracy International along with the Finnish ammunition manufacturer Lapua , or more officially Nammo Lapua Oy , which since 1998 is part of the Nordic Ammunition Group ( Nammo ) . Lapua opted to redesign the . 338 / 416 cartridge . In the new case design , particular attention was directed toward thickening and metallurgically strengthening the case ' s web and sidewall immediately forward of the web . In modern solid head 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 . 338 calibre Lock Base B408 full metal jacket bullet , modeled after its . 30 calibre Lock Base bullet configuration . The result was the . 338 Lapua Magnum cartridge which was registered with C . I . P . ( Commission Internationale Permanente pour l ' Epreuve des Armes à Feu Portatives ) in 1989 . With the procurement by the Dutch Army , the cartridge became NATO codified . The . 338 Lapua Magnum fills the gap between weapons chambered for standard military rounds such as the 7 . 62×51mm 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 . Like every other comparable big magnum rifle cartridge the . 338 Lapua Magnum presents a stout recoil . An appropriate fitting stock and an effective muzzle brake will help to reduce recoil induced problems , enabling the operator to fire more rounds before getting too uncomfortable to shoot accurately . Good factory loads , multiple projectile weights and factory special application ammunition 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 . Law enforcement and military users . The . 338 Lapua Magnum cartridge is in law enforcement or military use with : 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 U . S . military . On June 17 , 2008 , the U . S . government issued a market survey to support a requirement for a Precision Sniper Rifle ( PRS ) to possibly replace the currently fielded Bolt Action SOF Sniper Systems MK 13 ( . 300 Winchester Magnum ) and the M40 and M24 ( 7 . 62×51mm NATO ) chambered to safely fire factory produced " non - wildcat " . 338 caliber ammunition . Cartridge dimensions . Extremely thick - walled brass results in a 7 . 40 ml ( 114 grains HO ) 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 , semi - automatic , and automatic firearm s alike , under extreme conditions . . 338 Lapua Magnum maximum C . I . P . cartridge dimensions . All sizes in millimeters ( 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 , land width = 2 . 79 mm and the primer type is large rifle magnum . According to the official C . I . P . decisions and tables edition 2007 the . 338 Lapua Magnum case can handle up to 420 MPa ( 60 , 916 psi ) piezo pressure . This now prevails over the C . I . P . decisions and tables edition 2003 , that rated the . 338 Lapua Magnum at 470 MPa ( 68 , 167 psi ) maximum piezo pressure . The 470 MPa ( 68 , 167 psi ) maximum piezo pressure C . I . P . ruling for the . 300 Lapua Magnum cartridge , which is based on the same case , was not accordingly changed . In C . I . P . regulated countries every rifle cartridge combo has to be proofed at 125 % of the prevailing maximum C . I . P . pressure to certify for sale to consumers . According to the official C . I . P . ( Commission Internationale Permanente pour l ' Epreuve des Armes à Feu Portatives ) rulings the . 338 Lapua Magnum can handle up to P piezo pressure . This now prevails over the C . I . P . decisions and tables edition 2003 , that rated the . 338 Lapua Magnum at P piezo pressure . In C . I . P . regulated countries every rifle cartridge combo has to be proofed at 125 % of this maximum C . I . P . pressure to certify for sale to consumers . This means that . 338 Lapua Magnum chambered arms in C . I . P . regulated countries are currently ( 2013 ) proof tested at PE piezo pressure . Lapua is ambivalent on the maximum piezo pressure of this cartridge . In the article ' From an American dream to a Finnish success story ' by Janne Pohjoispää Lapua propagates the C . I . P . 2007 ruling of maximum piezo pressure . To further complicate matters the mentioned 56 , 000 CUP C . I . P . copper crusher pressure in this article would translate in ≈ C . I . P . piezo pressure according to a study on the conversion from CUP to PSI for rifle cartridges by Denton Bramwell . The C . I . P . 2003 ruling of piezo pressure is corroborated by Lapua Australia in the ' History and development of the . 338 Lapua Magnum ' article by Alan C . Paulson . A reverse engineering simulation with QuickLOAD internal ballistic software predicted that Lapua load their factory . 338 Lapua Magnum ammunition at ≈ piezo pressure as Alan C . Paulson asserts in his article . The large boltface combined with the high maximum pressure means that the . 338 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 high pressure loads can cause serious or fatal injury to the shooter and bystanders . The American . 338 - 378 Weatherby Magnum cartridge introduced in 1998 and the American . 338 Remington Ultra Magnum ( . 338 RUM ) cartridge introduced in 2000 are probably the closest currently ( 2007 ) commercially available ballistic twins of the . 338 Lapua Magnum . The . 338 - 378 Weatherby Magnum is however a belted cartridge and the . 338 Remington Ultra Magnum is a rebated rim cartridge . Supersonic range performance of the . 338 Lapua Magnum . Performance with C . I . P . conform cartridges . For a typical . 338 Lapua Magnum high end factory military sniper rifle like the Sako TRG - 42 with a long 305 mm ( 1 in 12 inch ) rifling twist rate barrel at sea level , is considered to be the maximum shooting distance for man sized targets . When using standard Lapua military 16 . 2 g ( 250 gr ) loads it has a supersonic range of under warm summer conditions at a muzzle velocity of . However , to be able to maintain 80 to 90 % hit probability on non - moving reactive army targets , this maximum shooting distance has to be reduced to at freezing point conditions or in Arctic winter conditions , when the muzzle velocity may drop to — i . e . only during optimal warm summer conditions the maximum shooting distance is realistically achievable . Loaded with more aerodynamic very - low - drag bullet s such as the traditionally lead cored 19 . 44 g ( 300 . 0 gr ) Lapua Scenar GB528 VLD bullet ( G1 BC = 0 . 736 ) 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 supersonic range of . 338 Lapua Magnum rifles can be improved . These longer very - low - drag bullets require a 254 mm ( 1 in 10 inch ) twist rate to stabilize them . Due to the lower practically possible muzzle velocities for a relative heavy bullet like the 19 . 44 g ( 300 gr ) Lapua Scenar GB528 VLD bullet it gains about extra supersonic range under International Standard Atmosphere sea level conditions ( air density ρ = 1 . 225 kg / m ) at a muzzle velocity of 837 m / s ( 2750 ft / s ) when compared to the standard 16 . 2 g ( 250 gr ) Lapua Scenar GB488 VLD at a muzzle velocity of 915 m / s ( 3002 ft / s ) . For significant supersonic range improvement the aerodynamic efficiency of the employed bullets has to be significantly improved without sacrificing a lot of practically achievable muzzle velocity - meaning that besides the coefficient of drag of the projectile weight is also an important parameter for its actual downrange flight behavior . The . 338 17 . 5 gram ( 270 gr ) Lost River Ballistic Technologies J40 match bullet made out of a copper - nickel alloy is one of the most aerodynamic . 338 calibre bullets available . It has a 1800 m ( 1969 yd ) 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 m ( 1969 yd ) feasible . Performance improvement experiments with non C . I . P . conform cartridges . Improvement beyond this standard while still using standard . 338 Lapua Magnum brass is possible , but the bullets have to be very long ( over 5 . 5 calibers in length ) and the normal cartridge overall length of 93 . 5 mm has to be exceeded making such cartridges wildcats . The common 254 mm ( 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 fast - twist bore . The firearm action and if a repeating arm is required the magazine ( s ) must also be able to cope with dimensional increases . 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 ≈ 0 . 93 – this Ballistic coefficient ( BC ) is calculated by its designer , Lutz Möller , and not proven by Doppler radar measurements ) . If Möller ' s assumptions are correct , the LM - 105 would have a supersonic range of ≈ 2000 m ( 2200 yd ) at a muzzle velocity of 915 m / s ( 3 , 002 ft / s ) under International Standard Atmosphere sea level conditions ( air density ρ = 1 . 225 kg / m ) . The 2010 version of the LM - 105 bullet has an overall length of 54 . 3 mm ( 2 . 14 in ) or 6 . 33 calibers 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 178 mm ( 1 : 7 inch ) progressive twist rate 900 mm ( 35 . 43 in ) long barrels with a 2° cone - angle ( the standard C . I . P . cone - angle for the . 338 Lapua Magnum is 6° ) cone area finished first and second at several long range competitions . Its most recent win ( 2007 ) was in an international Special Forces and police sniper competition in Switzerland against rifles chambered for 7 . 62×51mm NATO up to . 50 BMG at ranges from 100 m – 1 , 500 m ( 109 yd – 1 , 640 yd ) . The LM - 105 bullet exhibited its very low wind drift susceptibility notably at ranges beyond 800 m ( 875 yd ) . A real world average G1 BC of ≈ 0 . 90 to 0 . 93 is commonly adopted by the users of this bullet , for making long range trajectory predictions using ballistics calculators . The . 343 Lapua Magnum LM - 107 was a wildcat cartridge under development based on the standard . 338 Lapua Magnum cartridge case . The LM - 107 was hoped to boost the ballistic performance of the LM - 105 by achieving an increase in supersonic range . The 19 . 3 g ( 298 gr ) LM - 107 projectile design is 59 mm long and has a Haack profiled nose and an Adams profiled tail . The rifling twist rate for the . 343 Lapua Magnum LM - 107 wildcat cartridge was chosen at 180 mm ( 1 : 7 inch ) , Ø lands = 8 . 72 mm , Ø grooves = 8 . 45 mm and loaded with the LM - 107 projectile has a cartridge overall length of 107 mm . The length of the neck is increased from 8 , 31 to 8 , 50 mm to support the bigger LM - 107 bullet . Several other dimensions of the . 338 Lapua Magnum parental cartridge are also changed . The shoulder angle gets steepened from 40° to 60° and the body taper is set at 1° . The throat area is set at a 2° cone - angle . All this modifications make the . 343 Lapua Magnum a fairly comprehensively revised wildcat cartridge . Out of a 900 mm ( 35 . 43 in ) long progressive twist barrel Mr . Möller expected to achieve 909 m / s ( 2982 ft / s ) muzzle velocity . If Möller ' s design assumptions are correct the LM - 107 projectile with a calculated G1 BC of 1 . 02 will offer a supersonic range of ≈ 2170 m ( 2373 yd ) at a muzzle velocity of 909 m / s ( 2982 ft / s ) under International Standard Atmosphere sea level conditions ( air density ρ = 1 . 225 kg / m ) . . 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 bullet s result in very high muzzle velocities . The Finnish ammunition manufacturer Lapua got the . 300 Lapua Magnum C . I . P . 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 C . I . P . 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 . 33 ml ( 113 grains HO ) cartridge case capacity . . 300 Lapua Magnum maximum C . I . P . cartridge dimensions . All sizes in millimeters ( 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 , land width = 4 . 47 mm and the primer type is large rifle magnum . According to the official C . I . P . ( Commission Internationale Permanente pour l ' Epreuve des Armes à Feu Portatives ) rulings the . 300 Lapua Magnum can handle up to P piezo pressure . This now prevails over the C . I . P . decisions and tables edition 2007 , that rated the . 300 Lapua Magnum at P piezo pressure . In C . I . P . regulated countries every rifle cartridge combo has to be proofed at 125 % of this maximum C . I . P . pressure to certify for sale to consumers . This means that . 300 Lapua Magnum chambered arms in C . I . P . regulated countries are currently ( 2013 ) proof tested at PE piezo pressure . < br > 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 ( 68 , 000 PSI ) 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 ( 68 , 000 PSI ) loads can cause serious or fatal injury to the shooter and bystanders . The 7 . 62 UKM . The . 338 Lapua Magnum cartridge is also used as the parent case for the German designed 7 . 62 UKM , which is essentially a necked - down shortened version of the . 338 Lapua Magnum . The use of the . 338 cartridge case with its capability to operate at high chamber pressures resulted in magnum case capable of producing high muzzle velocities . The 7 . 62 UKM was developed by Michael Uekötter and was C . I . P . - certified in 2002 , making it an officially registered and sanctioned member of the Finnish " family " of super magnum rifle cartridges . The 7 . 62 UKM is not commercially available and currently exists only as a C . I . P . 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 7 . 62 UKM has a 5 . 84 ml ( 90 grains HO ) cartridge case capacity . 7 . 62 UKM maximum C . I . P . cartridge dimensions . All sizes in millimeters ( 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 = 7 . 62 mm , Ø grooves = 7 . 82 mm , land width = 2 . 79 mm and the primer type is large rifle magnum . According to the official C . I . P . ( Commission Internationale Permanente pour l ' Epreuve des Armes à Feu Portatives ) rulings the 7 . 62 UKM Magnum can handle up to P piezo pressure . This now prevails over the C . I . P . decisions and tables edition 2007 , that rated the 7 . 62 UKM at P piezo pressure . In C . I . P . regulated countries every rifle cartridge combo has to be proofed at 125 % of this maximum C . I . P . pressure to certify for sale to consumers . This means that 7 . 62 UKM chambered arms in C . I . P . regulated countries are currently ( 2013 ) proof tested at PE piezo pressure . < br > Wildcats . The . 338 Lapua Magnum case is also used as the parent case for a host of modified variants that are not officially registered with or sanctioned by C . I . P . or its American equivalent , SAAMI . Such cartridges which use commercial factory cases are generally known as wildcats . By changing the shape of standard factory cases ( decreasing case taper and / or changing the shoulder geometry ) the wildcatter generally increases the case capacity of the factory parent cartridge case , allowing more propellant to be used to generate higher velocities . 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 , 7 mm Fatso ) , . 30 ( . 30 - 338 Lapua ( Triebel ) , . 30 Wolf ) , 8 mm ( 8 mm - 338 Lapua ( Triebel ) , LM - 101 ) , . 338 ( . 338 Yogi , LM - 105 ) , . 343 ( . 343 Lapua Magnum LM - 107 ) , 9 . 3 mm ( 9 , 3 - 338 Lapua Magnum ( Triebel ) ) , . 375 ( 9 . 5×70 ELR ) and . 50 calibre ( . 510 Whisper ) variants . The current ( 2008 ) benchrest 5 - shot group world record holder Tom Sarver used a . 300 Hulk wildcat cartridge , which is basically a necked - down , blown out , shortened . 338 Lapua Magnum variant , to achieve a diameter 5 - shot group on 7 July 2007 .