The .338 Lapua Magnum Cartridge: Origin, Development and Future: Part I

In 1983 (sic), Research Armament Co., in the U.S. began development of a new, long-range sniper cartridge capable of firing a 250-grain, .338-inch diameter bullet at 3000 fps. After preliminary experiments, a .416 Rigby case necked down to a .338-inch was selected. Brass Extrusion Labs Ltd. of Bensenville, Illinois, made the cases, Hornady produced bullets, Research Armament built the gun under contract for the U.S. Navy. Subsequently, Lapua of Finland has put this caliber into production (Cartridges of the World, 8th edition [1]).

The precursor of the .338 Lapua Magnum was designed primarily for long-range military tactical shooting. A secondary design consideration was a cartridge that could be used in a General Purpose Machine Gun (GPMG). Sixteen years after its origin, the cartridge has been chambered in twelve tactical and game hunting turn-bolt rifles: Accuracy International SM; Arnold Arms Mark II; Dakota T-76 Longbow; ERMA SR-100; Harris Long Range; Heym Magnum; Keppler KS II; Mauser SR93; McMillan MCRT; RAI 300; Sako TRG-41 and TRG-S. With a rebated rim, the cartridge also has been chambered in the experimental Remington SR8 rifle known as the .338 RRR (Remington Rebated Rim — for review, see [2]). Finally, the caliber has been chambered in a new semi-automatic rifle, Barrett 98.   To my knowledge, this caliber has not been adapted for GPMG use.

Even though highly specialized rifles have been chambered for the .338 Lapua Magnum, the cartridge has not experienced wide adoption in neither police tactical nor military tactical arenas. Since the cartridge was designed for long-range tactical shooting, one would expect limited utilization as a police tactical cartridge due to fact that the majority of targets encountered are less than 100 meters. Several exceptions exist: 1) situations where a projectile with high kinetic energy is required in order to remove or to penetrate a barrier; i.e., cinder block wall etc., before reaching the target; and 2) specialized long-range tactical shootings; i.e., targets on airport tarmacs/runways, shopping malls etc.. Thus with these exceptions in mind, it seems reasonable to assume that the .338 Lapua Magnum is most suited as a military cartridge for targets extending beyond 1000 meters.

A review of existing military cartridges reveals that in the hands of a qualified shooter, the 5.56mm NATO (.223 Remington) is capable of a precision range up to 500 meters; the 7.62mm NATO (.308 Winchester) is capable of precision range up to 700 meters while the .338 Lapua Magnum extends the maximum precision range out to 1,300 meters and perhaps beyond [3]. But the .338 Lapua Magnum is not a common military cartridge; instead, on an ad hoc basis, the .300 Winchester Magnum and to a lesser extent the 7mm Remington Magnum are used to extend the range beyond what is found with the 7.62mm NATO. Finally, the .50 Browning is located at the end of the spectrum with a maximum range of 2,800 meters.

It seems reasonable to assume that the .338 Lapua Magnum would be a better intermediate between the 7.62mm NATO and the .50 Browning than either the 7mm Remington Magnum or the .300 Winchester Magnum. Some signs are emerging that this might be the case. Recently, over 300 Accuracy International’s Model AWM rifles in the .338 Lapua Magnum caliber went into service with the Dutch Army (Malcolm Cooper, Accuracy International [Portsmouth, England; Oak Ridge, Tennessee], personal communication). With the procurement by the Dutch Army, the caliber became NATO codified. The United Kingdom as well as Italy have both approved the .338 Lapua Magnum caliber for their services and Cooper expects that both nations will be purchasing rifles in the near future.

Why has it taken so long for the .338 Lapua Magnum to gain military acceptance? There are at least two reasons — perhaps more. Nick Steadman (Small Arms Data by Wire, East Sussex, UK [4]) suggests that the military is extremely reluctant to abandon existing NATO-specified ammunition. One of the best examples of this logic is when General Douglas McArthur selected the .30-06 Springfield as the cartridge for the M1 Garand rifle because at the time, the military possessed a very large surplus of .30-06 ammunition. However, Steadman believes that signs are emerging that the .338 Lapua Magnum is catching on with the military as a means to extend the range of the .300 Winchester Magnum — a view shared by Cooper.

I proposed that a second reason exists: A lack of adequate research to produce one or more highly accurate commercial cartridges, similar to what is found with several of the .308 Winchester cartridges carrying the “Match” designation utilized by police tactical, as well as the new 7.62mm NATO M118:LR cartridge utilized by military tactical. In addition to accuracy, adequate kinetic energy must be addressed, for the .338 Lapua Magnum is being promoted as “the” intermediate cartridge between the 7.62mm NATO and the .50 Browning. Thus, for this cartridge to be a true intermediate, it should not only be accurate but it should deliver the kinetic energy of a true intermediate to the target.

NOTE: Malcolm Cooper argues that a great deal of research has been performed on this cartridge by Accuracy International and Patria Lapua Oy during the previous ten years, and that these two companies together have accumulated more experience than anyone else (Malcolm Cooper, personal communication). His argument may be sound! However, three problems exist. 1) Much of the research, to my knowledge has not been published.   2) What we do know focuses on the .338 Lapua Magnum with the Lock Base projectile when mated with Accuracy International’s rifle because both cartridge and rifle were developed as a package. 3) Finally, the argument does not take into consideration the question of the lack of appropriate kinetic energy if the cartridge is to serve as a true intermediate between the 7.62mm NATO and .50 Browning — a point on which I shall focus within this article.

Until recently, Patria Lapua Oy (Finland) was the only manufacturer of .338 Lapua cartridge cases; however, Norma (Sweden) now has entered the market. Patria Lapua Oy continues to be the only manufacturer of .338 Lapua cartridges, however — offering three projectile formats: 250gr Lock Base High Performance Sniper (HPS), 250gr Mira and 260gr Forex Tactical. Patria Lapua Oy advertises its Lock Base design as providing, … superior accuracy at extra long distances, due to the extremely narrow base bleed. The Mira design is a spire point boat-tail intended for game hunting while the Forex design is new CNC-machined projectile with driving bands and a rear hollow chamber resulting in forward center of gravity, both characteristics necessary for game hunting in heavy brush. In the .338 Lapua Magnum configuration, the Forex is also intended for tactical shooting in situations where high kinetic energy is required. Finally, Patria Lapua Oy had advertised that an Armor Piercing Incendiary (API) projectile was undergoing development. Recently, development of this projectile was dropped due to problems dealing the timing of the ignition (Hanne Korteso, Patria Lapua Oy, personal communication); however, API can be obtained by special order (Malcolm Cooper, personnel communication).

The Lapua .338 Lapua Magnum 250gr Lock Base HPS cartridge is the big brother of the highly precise Lapua .308 Winchester 170gr Lock Base HPS cartridge. Recently, Patria Lapua Oy retired the 250gr Lock Base projectile; at the same time, it introduced a second 250gr projectile in the Scenar configuration (Figure 1). The original Scenar projectile is advertised as a hollow point boat-tail, … tailored especially for competition and sniper shooting. As a hollow point projectile, military use is permitted for those countries not bound by the First Hague Convention (for review, see [5]). The new 250gr Scenar projectile was designed without a hollow point for those countries that must satisfy the First Hague Convention (Ville Ruuskanen, Patria Lapua Oy, personal communication).

Thus, the 250gr Lock Base projectile, available in the only .338 Lapua Magnum HPS cartridge, will be replaced by the 250gr Scenar without a hollow point. I’m assuming that the 250gr Lock Base did not live up to the expectations of Accuracy International and Patria Lapua Oy. The aft portion of the Scenar has a better design than the Lock Base for this particular caliber (Malcolm Cooper, personnel communication). One wonders whether the .338 Lapua Magnum caliber would become more popular as a police and military tactical cartridge, if manufacturers, in addition to Patria Lapua Oy, would offer “Match” cartridges with different bullet weights/configurations in this caliber?


In order to understand the .338 Lapua Magnum cartridge of today, a review of its origin and early development would be useful. At the same time, we should examine the origin and early development of the platform that launched the projectile because it influenced the status of the cartridge today. From there, we shall examine the cartridge up to the present. I shall argue a theme: The cartridge has yet to be developed to its full potential. Finally, in an attempt to open a dialog with readers who might be interested in working to establish this cartridge’s full potential, I shall present data from a rifle I designed and which was constructed by Willi Wordman (Seahorse of Michigan, Grosse Pointe Woods, MI). The rifle was constructed around an “up-graded” .338 Lapua Magnum cartridge. Definition of this up-grade is Sierra’s (Sedalia, MO) 300gr MatchKing (#9300) propelled by VihtaVuori Oy (Finland) propellants. Because the rifle’s chamber was designed to hold tight tolerances for the 300gr MK, we have not examined the 250gr Lock Base nor the 250gr Scenar from Patria Lapua Oy. These projectiles as well as the re-designed 250gr Scenar, when available, are projects for the future.

It is my hope that others will participate in researching .338 Lapua Magnum’s full potential as a long-range tactical cartridge.


The origin of the .338 Lapua Magnum was Rogers, Arkansas with the creation of a new manufacturing firm called Research Armament Prototypes Industries, but today usually referred as Research Armament Industries (RAI). Jerry Haskins (deceased) was the driving force of the new firm and was instrumental in product design. In addition to Haskins, Edward B. Dillon (Steamboat Stock Works, Colorado Springs, CO.) assisted in the formation of the company; was largely responsible for writing proposals and administering contracts for the Department of Defense; and assumed the role of director of military sales.

In response to a Request for Proposal (RFP) from the U. S. Navy, RAI constructed 125 .50 Browning tactical turn-bolt, single-shot rifles (Model 500) and 125 7.62mm NATO/8.58x71mm tactical turn-bolt, magazine rifles (Model 300). This article will not examine the Model 500; but instead will focus on the Model 300 for this represented the original platform for the cartridge that today is known as the .338 Lapua Magnum. An evaluation of the Model 500 can be found by Jim Shults [6].

The initial two prototype rifles made by RAI were a .300 Winchester Magnum and a .50 Browning. The RFP required a 30-caliber projectile to penetrate five layers of Kevlar at 1,500 yards; but it was soon discovered that the .300 Winchester Magnum was unable to achieve this task — a task that even by today’s standards would be difficult to achieve. RAI turned to the .378 Weatherby cartridge case for launching a .338 projectile. This cartridge case was soon abandoned because of feeding problems due to the cartridge case’s belt. Next, a blown out Weatherby cartridge case minus a belt was considered. Boots Obermeyer’s (Obermeyer Rifled Barrels, Bristol, WI) research notes reveal that this cartridge case had very little body taper which would not be ideal for extract reliability and recommended that it should be abandoned as well.

A large capacity cartridge case without a belt was required. At the time, James J. Bell Jr. (a.k.a. Jim) of Brass Extrusion Laboratories Ltd. (Bensenville, IL) was producing high quality .416 Basic and .416 Rigby cartridge cases and was approached by Haskins in the spring of 1982 to run a series of tests on a .338/.416 cartridge. Initial cartridge cases from Bell were the .416 Basic with .416 Rigby headstamps.

It is generally accepted that the .416 Rigby cartridge case served as the parental case that Jim Bell and Boots Obermeyer used to create the .338 Lapua Magnum as a wildcat. However, Bell (currently, MAST Technology, Las Vegas, NV) informed me that the cartridge case that we know today as the .338 Lapua Magnum is of novel design — a point which Patria Lapua Oy emphasizes in its current advertising literature. Even though the .416 Basic was used as a starting point, according to Bell, he designed the interior of the new cartridge case de novo. In addition, Obermeyer’s design and research notes clearly show the design steps on the exterior of this new cartridge (Figure 2). Part of his design included the possibility that the cartridge might be adapted as a GPMG cartridge.

The .338 projectile was novel as well. Initially, Haskins wanted Sierra to design the projectile, but they showed no interest. Bell recommended Hornady Manufacturing (Grand Island, NE) instead. Ed Dillon was responsible for working with Steve Hornady and his staff; and from this interaction, a novel 250gr boat-tail projectile was designed.

Based upon these findings, it seems reasonable that one can argue that the original cartridge case and projectile were novel. However, some might argue that the origin of the cartridge case is the .416 Rigby. If any parental cartridge case does exist in this scenario, it would have to be the .416 Basic and not the .416 Rigby. Clearly the projectile is novel. Today, the three men intimately involved in the project; i.e., Bell, Dillon and Obermeyer believe the cartridge they created in 1982 was novel.

What name was given to the new cartridge? Unfortunately, the cartridge has been known by several names until Patria Lapua Oy started manufacturing and christening it the .338 Lapua Magnum. Obermeyer’s research notes reveal .338 Sniper and .338/.416 Sniper as well as 8.58×71. Bell determined the metric name after being instructed by Obermeyer of the European practice. However, around the shop Bell tended to call the cartridge, Our sniper round. Haskins and Dillon referred to the cartridge as the .338/.416 while Jim Shults, in an article published in Gung-Ho magazine, referred to the cartridge as the .416/.338 even though a box of ammo pictured in the article is labeled .338/.416 [6]. At one time, Haskins considered naming the cartridge, the .338 KEITH — in honor of Elmer Keith. Keith, the famous gunwriter with a passion for large-bores, had recently died; however, the idea was not pursued. Today, Dillon possesses cartridge cases without headstamps in boxes labeled .338/.416. The metric designation of 8.58x71mm was insisted upon by Crane Naval Weapons Center, (Crane, IN) and was picked up by Frank Barnes in Cartridge of the World, 6th edition.

In addition to contributing to the design of the cartridge case, Obermeyer was responsible for making a pressure barrel and testing loads. His early studies focused on IMR 7828, but with hindsight, he now feels that IMR 7816 was the best propellant tested. From 95gr to 97gr, chamber pressures ranged from 55,400 to 57,200 psi with muzzle velocities ranging from 2923 to 2979 fps. However according to Dillon, the Navy wanted to use IMR 4350 as the propellant which at 90gr, the chamber pressure registered 51,400 psi while at 95gr, the chamber pressure rose to 63,000 psi with an estimated muzzle velocity of approximately 2800 fps (Obermeyer moved to other projects before measuring MVs for IMR 4350). To Obermeyer, the best propellant appeared to be IMR 7816 as it provided a bit more velocity and reduced the air space that acts as a cushion to the primer. In conclusion, the participants designing and constructing the cartridge felt the IMR 7816 was a better propellant, but it was not used because of the wishes of the Navy.

Obermeyer’s research notes reveal planned protocols to test the cartridge on the range, but the tests never occurred. The reason is that he loaned RAI four neck sizing dies and other items required for loading. RAI had been using a three-die set and up to that time, were losing most of their cartridge cases — they were desperate for cartridges for rifle testing. Unfortunately, the dies were never returned to Obermeyer and he discontinued testing, particularly testing with different propellants.

One of the major problems with the early cartridge design was that Bell and Obermeyer were not being paid for their efforts, and were forced to walk away from the project. The desire to continue the project was missing. Today, Boots Obermeyer provides an interesting overview of that period.

My work was the case design and getting the needed test barrels. I had to make the form dies to do this. The case used was straight .416 cases. Jim Bell looked at the interior design such as the head to be sure it had the strength needed. Also, he had to make

reduction dies for production if we got beyond the test part of the project. Had we kept on and got into range testing we might have made some changes. The problem was no pay, no work for both of us. There are a lot of people in this that make their money by spreading the BS like Jelly and often a lot of good ideas get dropped.

In hindsight, Obermeyer feels that he might had experimented more with his barrels and the cartridge that later would be known as the .338 Lapua Magnum. His hindsight is based upon a somewhat recent experience. During the Gulf War, Remington Arms Co. was interested in a long-range tactical based on the 8mm Remington Magnum with an improved .338 projectile design by Hornady. Obermeyer’s previous research with 30 calibers had shown that greater land height gave improved barrel life and, at the request of Remington, he began a research project with the 8mm Remington Magnum cartridge to determine whether he would observe similar results or not. Early results were extremely good, but the war ended before the project could be completed. Had Bell and Obermeyer continued with the 8.58x71mm cartridge project, Obermeyer is convinced that he would have explored a deeper rifling 5R design for this new caliber. With regard to the 8mm Remington Magnum project, he plans to finish it, but at this time, he has no plants to examine a deeper rifling 5R design for the .338 Lapua Magnum.

With the exception of using different barrel lengths, my findings — using Ed Dillon’s notes and memory — does not reveal additional research on improving the ballistics of the cartridge by RAI up to the time that Patria Lapua Oy began manufacturing the cartridge. It seems reasonable to assume that the .338 Lapua Magnum cartridge did not get off to an ideal start as a precision long-range tactical cartridge. Had Bell and Obermeyer continued their testing, today the .338 Lapua might be a better cartridge.


After the American origin, the current .338 Lapua Magnum cartridge was developed as a joint venture between Accuracy International and Patria Lapua Oy (Malcolm Cooper, personal communication). The cartridge manufacturer strengthened the cartridge’s web and designed a projectile modeled after its 30 caliber Lock Base configuration. The result was the .338 Lapua Magnum cartridge which is now registered with C.I.P. (Commission Internationale Permanente Pout L’Epreuve Des Armes A Feu Portative).

In concert with Patria Lapua Oy activities, Accuracy International developed a tactical rifle based upon its well-known AW system during the late 1980’s. The combination came into full production in the early 1990’s.

The .338 Lapua Magnum cartridge case’s manufacturing process has not been automated completely (Ville Ruuskanen, Patria Lapua Oy, personal communication). The last draw step is performed manually which increases the cost of manufacturing. It seems reasonable to assume that Patria Lapua Oy believes that when the cartridge achieves widespread military adoption, the last draw step probably be automated. As a point of interest, all of the draw steps in the new Norma cartridge are fully automated (Roger Johnston, NECO; personal communication). Finally, my experience with .338 Lapua Magnum cartridges cases manufactured by Patria Lapua Oy is that the flash hole is off-center in approximately 20% of the cases examined [7 – Figure 1]. Initial examination of Norma .338 Lapua Magnum cartridge cases does not reveal off-centered flash holes.


The RAI Model 300’s origin begin in Rifle, Colorado. On June 3, 1974, Jerry Haskins filed a patent entitled, Bolt Action for Repeating Rifle (Patent No. 3979849). The patent was issued slightly more than two years later on September 14, 1976. The patent stated 12 claims including, … a plurality of circumferentially spaced, radially inwardly extending arcuate locking lungs secured inside said rear receiver ring and separated from each other by axially extending spaces; a pair of spaced, elongated receiver rails extending between, and interconnecting, said forward and rear receiver ring, the space between said rails being aligned with said inclined ramp, and each of said rails having being relieved over a portion of the length thereof and adjacent the space therebetween;... In non-legalese English, the locking lugs were located on the rear of the bolt and engaged with the rear receiver ring; while the bolt possessed two rails which assisted in guiding the bolt forward. It appears that the location of the locking lugs at the rear of the bolt and engaging with the rear receiver was detrimental to the promotion of .338 Lapua Magnum as a long-range tactical cartridge.

The RAI Model 300 construction began during the early 1980’s. The rifle’s appearance was novel for the time (Figure 3). It possessed a modular design and was intended to shoot either 7.62mm NATO or 8.58x71mm. This convertibility of calibers was accomplished by changing barrels and by changing bolt heads from the same bolt. Thus, two barrels and two bolt heads were a part of the Model 300’s package.

Rifle barrels were made by H-S PRECISION, then located in Prescott, AZ, and were fluted and tapered. The stock was influenced by the Draganov design and provided an adjustable comb as well as a length of pull controlled by the lower stock extender. Trigger, similar to the Winchester’s Model 70, was adjustable. The rifle’s forearm possessed a tuning rod fitted into a lead plug, both held by bronze screw, which in turn was attached to the receiver. When the rifle was fired, the harmonics of the barrel were transferred to the receiver and then into the tuning rod, which in turn dampened the vibrations before the projectile left the muzzle.

Originally, the bipod was attached to the front of the receiver, but Navy insisted that it be moved to the forearm even though it would interfere with the operations of the tuning rod. The hole left in the receiver was used for the magazine latch. The original scope base was a ranging scope base that could elevate the rear of the scope in preset increments. The ranging scope bases were difficult to machine; and the Navy showed no interest in them, so they were soon discontinued.

During the early testing, the reticles of Weaver scopes being used by RAI jarred loose (Note: A Weaver scope is pictured in Figure 3). Haskins asked Leupold to construct a more stable scope. Leupold’s first offering was a fixed 10X scope, which was followed by a 14X and then by a 16X configuration. The scopes possessed a 30mm tube, external adjustment knobs, and a mil-dot reticle. The Schults’ Gung-Ho article [6] discussed and shows an image of one of these scopes. Schults noted that even though the scope possessed no identification markings, it was clearly made by Leupold. Based upon this information, it’s reasonable to speculate that the scopes provided to RAI represented precursors to Leupold’s Mark series (Note: A Leupold scope is pictured on a Model 500 in Figure 3 of the sidebar article).

In hindsight, the location of the locking lugs were detrimental, especially to the larger of the two cartridges that the rifle accommodated. The 8.58x71mm cartridge was longer than the 7.62mm NATO; and as a result, required a long magnum action. Today, Dillon believes that because the locking lugs were located on the rear of the bolt, the bolt would compress during firing, while at the same time, the receiver would elongate — both events leading to a change in the headspace. It’s safe to conclude that this situation would not be conducive for accuracy. Haskins’ patented receiver, which later became the basis for the receiver of the RAI Model 300 was designed for low pressure cartridges such as the 7.62mm NATO, but clearly was not designed for a high pressure cartridge such as the 8.58x71mm.

Later, when Patria Lapua Oy manufactured .338 Lapua Magnum cartridges, they would produce a cartridge cases with brass softer than what was being produced by most manufacturers. High chamber pressures also became a problem which were subsequently addressed by Patria Lapua Oy and are emphasized in their advertising literature of today.

Even though the RAI Model 300 has several novel design components — some of which can be seen on tactical rifles of today — the rifle was not an ideal platform for .388 Lapua Magnum to launch its career.


            In the 1993 book by John L. Plaster (Minnesota National Guard Counter Sniper School St. Paul, MN) entitled, The Ultimate Sniper [8], Plaster briefly covers the .338 Lapua’s Magnum’s specifications, contrasts its future against the .300 Winchester and the .50 Browning, but he provides no opinion of cartridge itself. However in 1995, Nick Steadman in an article entitled, 21st Century Ammo, published in Fighting Firearms [9], revealed that Accuracy International (Portsmouth, UK) was promoting a .338 Lapua Magnum system as a lighter alternative to the .50 Browning. In addition, he pointed out that despite attempts by Patria Lapua Oy to develop a .338 Lapua Magnum API, from the kinetic energy aspect the caliber will not be able to compete with a .50 Browning projectile. Also at that time, he claimed that the cartridge was attracting widespread tactical interest beyond the United Kingdom. In Germany for example, it was being considered alongside the .300 Winchester Magnum for the Bundeswehr’s new G22 sniper rifle requirement. For the final decision, the Bundeswehr chose Accuracy International rifle in the .300 Winchester Magnum caliber rather than in the .338 Lapua Magnum and eventually over 1300 of these rifles will be integrated with German military. The G22 already has been deployed in Bosnia (Malcolm Cooper, personal communication).

Up to this time, the military clearly were evaluating the cartridge, but what about police tactical? In a 1996 book by David M. Lauch (D & L Sports, Gillette, WY) entitled, The Tactical Marksman [10], I can not find any references to the .338 Lapua Magnum. Assuming I didn’t miss anything, I’m sure Dave was aware of the cartridge at the time, but it probably was not included because he felt that it did not have a viable application in a police tactical book.

By 1998, Mike Lau (Texas Brigade Armory, Duncanville, TX) published a book devoted to both police and military tactical entitled, The Military and Police Sniper [11] which reviews some of the history of the .338 Lapua Magnum cartridge and points out some of its advantages over the .50 Browning; i.e., lower ammunition and rifle weight and reduced blast signature. In his book, Lau makes a comment that supports a position I took earlier this year [3]: The .338 could do more than fill the gap between the 7.62x51mm and Cal. 50, it could replace the .50. However, there is one drawback, a more destructive .338 round needs to be developed to replace the .50’s role in engaging light armor and other heavy equipment.

Will a projectile weight greater than 250gr enhance the kinetic energy potential on the .338 Lapua Magnum cartridge — particularly for anti-material tactical shooting? First, Steadman [9], then myself [3], and finally Lau [11] have raised the issue of inadequate kinetic energy at the target site with the .338 Lapua Magnum’s 250gr projectile. In order to address this issue, we shall examine Sierra’s 300gr MK, as well as some preliminary studies on a novel 350gr, SAE 660 bronze, 9 ogive, boat-tail projectile in the .375 caliber using the .338 Lapua Magnum cartridge case as a parental case. Studies did not lead to actual testing because we felt that it was not worthwhile to continue..

NOTE: During the preparation of this article, Jim Dunn, Research and Development Engineer at ITT Systems and Sciences (Colorado Springs, CO) brought to my attention that Patria Lapua Oy lists in their advertising literature that the following .338 projectiles: 250gr Lock Base (B 408), 250gr Scenar (GB 488) and 250gr Forex (EX 482) possesses diameters of 0.339″ (8.61mm). On the other hand, Sierra lists in their advertising literature that the following .338 projectiles: 215gr GameKing (2610), 250gr GameKing (2600) and 300gr MatchKing (9245) possesses diameters of 0.338″ (8.59mm). These diameters were verified by measuring the diameters of Sierra’s 300gr MatchKing (0.338″ [8.59mm]) and Patria Lapua Oy’s Lock Base (0.339″ [8.61mm]). Jim’s concern, one that I share, is that you, the shooter, should know the groove diameters of your .338 Lapua Magnum barrels when using either Patria Lapua Oy or Sierra .338 projectiles. With a difference in projectile diameters, chamber pressures clearly would probably vary from one brand of projectile to the next. Out of curiosity, I examine one of the original Hornady .338 projectiles left over from the RAI Model 300 project. It measured 0.338″ or 8.59mm.


            I designed and Willi Wordman constructed the tactical rifle for testing the Sierra 300gr MK (Figure 4). Wordman utilized a Sako TRG-S action (Accuflite, Export, PA) which consists of a cold-hammer forged receiver, a short 60? bolt tilt with three locking lugs and a TRG tactical bolt handle. Barrel (Krieger Barrels, Inc., Germantown, WI) was chrome moly, standard Palma Match with a 1/10-twist right hand with 6 groves. In addition, the barrel had a breech diameter of 1.200″, a muzzle diameter of 0.930″, and 10 flutes with a flute diameter of 0.187″. The barrel’s length was 27″ and with addition of a muzzle brake, the final length came to 30″. The PGRS muzzle brake was designed by Bruce McArthur (Flint & Frizzen, Clarkston, MI) for the .50 Browning, and has been rated as the muzzle brake with the lowest recoil when compared to other muzzle brakes (12). Wordman lapped the locking lugs and trued the barrel to the receiver.

The barrel and receiver were cryogenic treated (Cryo-Tech, Inc. Hazel Park, MI) and then stocked with an M-89 Tactical Stock (Harris Gun Works, Phoenix, AZ) with a three-way adjustable butt assembly and an adjustable cheek piece. The scope utilized was a Leupold 50mm Long Range Target with 0.25 MOA Dot converted by Premier Reticles, Inc. (Winchester, VA) to a 14.5×35 configuration.

Wordman and Dave Manson (then at Clymer Manufacturing, Rochester Hills, MI) designed a chamber reamer with tight tolerances built around the Sierra 300gr MK. Manson (now at Loon Lake Precision, Inc., Grand Blanc, MI) named the new design the .338 Lapua Magnum Special (Figure 5). Krieger rough reamed the barrel with a 338 Winchester Magnum reamer while Wordman finished by hand the reaming with the .338 Lapua Magnum Special reamer.

NOTE: Actual loading data will not be provided in this article. The reason is that our loads were established for a rifle chambered for the .338 Lapua Magnum Special. To my knowledge, no one has chambered a rifle for this caliber other than us. If you decide to build a rifle in this caliber, I shall be happy to share our loading data with you.

Load development, using Patria Lapua Oy’s cartridge cases, VihtaVuori Oy N165 and N170 propellants, Federal 210 Match primers and moly-coated (moly-coating via the NECO method) Sierra 300gr MK projectiles, were performed by Pat Murphy with Dr. Steven Faber monitoring the chamber pressures using his designed Fabrique Scientific Peak Strain Meter (Fabrique Scientific, Batavia, IL). For additional information on the Fabrique strain meter, see [13].

Initial loads utilized N165 and generated muzzle velocities in the 2500 fps range with chamber pressures in the low 50,000s psi. With low chamber pressures such as these, McAuthur’s PGRS muzzle brake is not operational and perceived recoil will be fierce. Loads with N165 were worked up to a maximum muzzle velocity of 2708 fps with a maximum chamber pressure of 60,206 psi (Figure 6). Next, loads with N170 were worked to a maximum muzzle velocity of 2806 fps with a maximum chamber pressure of 62,852 psi (Figure 7). Beyond this point, chamber pressures increased dramatically accompanied by muzzle velocities that had essentially plateaued. With these higher chamber pressures, McAuthur’s PGRS muzzle brake became fully operational and the perceived recoil was similar to that of a .243 Winchester (consensus opinion of 10 shooters over a period of one year). Upon ejection from the chamber, cartridge cases were cool to the touch, primers showed minor flatness and case stretching in general were not detected. One exception of 0.004″ was detected. Overall, the cartridge case showed no signs of damage and subsequently, some of these cartridge cases have been reloaded up to eight times. At the fifth reloading, the cartridge cases require trimming.

Actual Performance – This cartridge is not designed for short distances nor does it perform well at short distances. Generally, five-shot groups at 100 yards averaged at 1.25″ (1.25 MOA) while those at 200 yards averaged at 1.50″ (0.75 MOA). These values led us to believe that the projectile was beginning to stabilize by 200 yards and the MOAs would improve with additional yardage. Rather than conducting tests at 300, then 600 yards, I decided to take advantage of a two-hour window — down time during a recent black powder cannon shot — to shoot at the 1000-meter (1096-yard) rifle range located at the military reservation called Camp Grayling (Grayling, MI).

Thus, on a sunny day this past July, at approximately 1:00 pm, with temperature of 86? F, winds 10-15 mph at 6:00 o’clock, and a mirage that would entice any shooter to take Dramamine, I had only enough time to set up a target and prone-shoot one five-shot group. The intensity of the mirage required me to use the lowest power on the scope – 14.5X. With the first shot, I thought the JBM Small Arms Ballistics (Las Cruces, NM) had failed me as the first projectile was three feet over the target — horizontally, it was also off by three feet as well. Wordman, using a 60X spotting scope, reminded me of the thermals and the lift they were creating. The thermals and the stout-tail wind clearly would account for the overshoot. Finally, after corrections, a 4.796″ (0.436 MOA) five-shot group at 1000 meters or 1096 yards was obtained (Figure 8).

Was my five-shot group luck or was it representative of what the rifle and cartridge are capable of achieving? I’m convinced this rifle and cartridge can exceed my group in the hands of more experienced shooters under better conditions. I’m only on the rifle range twice a month max. and don’t shoot competition. Soon we shall return to Camp Grayling for some early morning shooting with some aspiring Palma Team shooter such as Leo Cebulla. I predict the rifle and cartridge will consistently shoot under three inches.

Overview of Theoretical Performance – The Lapua 250gr Lock-Base projectile (B408) has a reported sectional density of 0.313 and a ballistic coefficient of 0.661; and when it is a component of the .338 Lapua Magnum cartridge, it has a reported muzzle velocity of 3002 fps. [14]. The Sierra 300gr MK projectile (#9245) has a reported sectional density of 0.375 and a ballistic coefficient of 0.768 [15]. When loaded in a .338 Lapua Magnum cartridge case, we have been able to obtain a high degree of accuracy at 1000 meters with measured muzzle velocities up to 2806 fps with measured maximum chamber pressures up to 62,852 psi.

Utilizing JBM Small Arms Ballistics program, at 1000 meters the 250gr Lock Base displays a velocity of 1629 fps with a kinetic energy of 1473 ft/lbs. On the other hand, the 300gr Sierra MK displays a velocity of 1648 fps with a kinetic energy of 1809 ft/lbs. Same velocity with a difference in kinetic energy of 336 ft/lbs. What have we gained by using this heavier projectile? We may have gained in accuracy. However, only a good number of shooters shooting this round, over a period of time will determine whether this is true or not. Because the recoil is prominent, I suspect the cartridge’s accuracy potential will not be determined in those competition shootings where muzzle brakes are not allowed. Without the expertise of competition shooters, finding the cartridge’s potential may take a fair amount of time. Finally, we have not gained much in kinetic energy with the 300gr over the 250gr.

If the goal is to make the .338 Lapua Magnum, using a 300gr projectile, the intermediate between the 7.62mm NATO and the .50 Browning, I can’t see it happening. It didn’t occur for the 250gr projectile, and my findings convince me that it will not occur for the 300gr projectile. The required kinetic energy is lacking. Can the weight of the projectile be increased? Yes — this can be accomplished by one of four ways: increasing the length of the projectile, increasing the diameter of the projectile, increasing the density of the projectile or some combination of the three.

We examined the possibility of using a 350gr projectile (SAE 660 bronze) in .375 while keeping the overall length of the cartridge the same as the 300gr projectile in .338. The reason for maintaining the existing overall length is because to utilize a cartridge longer than the .338 Lapua Magnum would require a longer action. If a longer action is required, then why not go to a new cartridge case with a greater capacity?

Unfortunately, the aft portion of the projectile takes too much space in the cartridge case (Figure 9). Examination of bronze projectiles in the .350 caliber were not attempted because it seemed obvious to us that even though the .350 has a smaller diameter than the .375, it — like the .375 — would require a cartridge case larger than the current .338 Lapua Magnum as well.

At this point, I don’t see any quantum gains leading to an ideal projectile with a weight greater than 300gr using the .338 Lapua Magnum cartridge case. Small gains are possible, but not quantum gains. Maintaining the overall length, a projectile of 325gr seems like a realistic goal that can be achieve either by increasing the caliber or increasing the density of the projectile. In my opinion, the gains in kinetic energy would be minimal.

The benefit of a 300gr plus projectile for anti-personnel purposes is its inherent ability to resist wind deflection. According to Jonathan M. Weaver, Jr. in an Aberdeen Proving Ground technical report, the only uncontrolled variable facing the sniper in the future with will be wind [16]. Clearly the .338 in a 300gr plus projectile — experiencing stiff wind deflection, would yield superior performance over the 7.62mm NATO or the .300 Winchester Magnum.


            The .338 Lapua Magnum has the potential to be an ideal very long-range anti-personal tactical cartridge, but may be facing a tough struggle and may not succeed. In my judgment, it will never be an ideal very long-range anti-material tactical cartridge. The required kinetic energy is lacking. On the other hand for long-range anti-personnel, what is required is additional research focusing on different projectiles with different configurations and weights.

The only commercial tactical loading; i.e., Patria Lapua Oy’s 250gr Lock Base appeared not to be successful and as a result, was replaced by a new 250gr Scenar. Will this new projectile be successful in the eyes of Patria Lapua Oy? Signs are emerging that it may well be a good projectile. Dr. Geoffrey Kolbe (Border Barrels Ltd., Newcatleton, Scotland) related to me that Malcolm Cooper had informed him that during a very recent UK Ministry of Defense trails, the new .338 Lapua Magnum out had performed the .50 Browning in accuracy, resistance to wind and flatness of trajectory. However, the .50 outperformed the .338 Lapua Magnum in delivered kinetic energy (Kolbe, personal communication).

Competition shooters have not become enamored with the .338 Lapua Magnum because their interest in a projectile’s terminal kinetic energy is not high. Couple that to the fact that a muzzle brake is required to shoot more than ten rounds, it will be difficult to find many competition shooter examining Sierra’s 300gr MK in a .338 Lapua cartridge case or in a wildcat of that case. Finally, the fact that .338 projectiles have different diameters, depending upon the manufacturer, will not be helpful.

Unless someone takes an interest in the .338 Lapua Magnum, I predict that it may continue to “float” as it has for the past 16 years. Wordman and I for have moved on. We are interested in kinetic energies greater that what the .338 Lapua Magnum can offer; and thus, we now focusing our attention on a new .408 caliber based on the .505 Gibbs cartridge case called the .408 Cheyenne Tactical (for background, see [7]). This cartridge at 440gr comes closer to being an intermediate between the 7.62mm NATO and .50 Browning than any other tactical cartridge. It would also be ideal as a GPMG and could be adopted to the M240 (a.k.a. FM MAG 58).


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  1. Wilson, M. 1998. The Remington SR8. Tactical Shooter, Vol. 1, No. 4, 9-14.
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Robert Dwayne

Robert Dwayne

To say that I am an outdoors enthusiast is probably an understatement. I am hyper passionate about everything outdoors: hiking, survival, hunting. On this website I am sharing my stories and experiences, and I hope you'll find inspiration to take up your own adventures!