The .300 Lapua Magnum (7.62×70mm) is a rimless, bottlenecked,

centerfire Two rounds of .357 Magnum, a centerfire cartridge; notice the circular primer in the center A center-fire (or centerfire) is a type of metallic cartridge used in firearms, where the primer is located at the center of the base of its casing (i. ...

cartridge developed for long-range

rifle A rifle is a long gun, long-barreled firearm designed for accurate shooting and higher stopping power, with a gun barrel, barrel that has a helical or spiralling pattern of grooves (rifling) cut into the bore wall. In keeping with their focus o ...

s. The parent case of the .300 Lapua Magnum is the .338 Lapua Magnum necked down to a smaller caliber. The .338 cartridge case was selected to withstand high chamber pressures. Combining these high pressures with smaller, lighter

bullet A bullet is a kinetic projectile, a component of firearm ammunition that is shot from a gun barrel. They are made of a variety of materials, such as copper, lead, steel, polymer, rubber and even wax; and are made in various shapes and constru ...

s than its parent case, .300 Lapua Magnum loadings have high muzzle velocities.

History

The Finnish

ammunition Ammunition, also known as ammo, is the material fired, scattered, dropped, or detonated from any weapon or weapon system. The term includes both expendable weapons (e.g., bombs, missiles, grenades, land mines), and the component parts of oth ...

manufacturer

Lapua Lapua (; ) is a List of cities and towns in Finland, town and municipalities of Finland, municipality in Finland's South Ostrobothnia regions of Finland, region. It is located next to the Lapua River. The town has a population of () and cov ...

obtained a C.I.P. certification for the .300 Lapua Magnum, so it became an officially registered and sanctioned member of the Finnish 70 mm family of super magnum rifle cartridges. The .300 Lapua Magnum is no longer commercially available. It is still used by a few shooters, who produce the cases from .338 Lapua Magnum cases by reshaping the shoulder and neck, and

handloading Handloading, or reloading, is the practice of making firearm cartridges by manually assembling the individual components ( metallic/ polymer case, primer, propellant and projectile), rather than purchasing mass-assembled, factory-loaded com ...

it with .30 caliber bullets. Up to the C.I.P. decisions and tables edition 2007 the .300 Lapua Magnum was rated at P_max piezo pressure, This very high outdated P_max has been reduced by the C.I.P. since then to P_max.

Cartridge dimensions

The .300 Lapua Magnum's case has a 7.34 mL (113

grains A grain is a small, hard, dry fruit ( caryopsis) – with or without an attached hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and le ...

of water) capacity. The exterior shape of the case was designed for reliable case feeding and extraction in

bolt-action Bolt action is a type of manual Action (firearms), firearm action that is operated by ''directly'' manipulating the bolt (firearms), turn-bolt via a cocking handle, bolt handle, most commonly placed on the right-hand side of the firearm (a ...

rifles, semi-automatic and

automatic firearm An automatic firearm or fully automatic firearm (to avoid confusion with semi-automatic firearms) is a self-loading firearm that continuously Chamber (firearms), chambers and fires Cartridge (firearms), rounds when the trigger (firearms), trigger ...

s, including under extreme conditions.

.300 Lapua Magnum maximum C.I.P. cartridge dimensions. All sizes in millimeters (mm). The common

rifling Rifling is the term for helical grooves machined into the internal surface of a firearms's barrel for imparting a spin to a projectile to improve its aerodynamic stability and accuracy. It is also the term (as a verb) for creating such groov ...

twist rate Rifling is the term for helical grooves machined into the internal surface of a firearms's barrel for imparting a spin to a projectile to improve its aerodynamic stability and accuracy. It is also the term (as a verb) for creating such groov ...

for this cartridge is 240 mm (1 turn in 9.45 inches), with 4 grooves. The diameter of the lands is 7.62 mm; the diameter of the grooves is 7.82 mm. Land width is 4.47 mm and the primer type is large rifle magnum. According to the C.I.P., the .300 Lapua Magnum can handle up to P_max piezo pressure. In C.I.P. regulated countries, every rifle and cartridge combination must be proof tested at 125% of the maximum C.I.P. pressure to be certified for sale to consumers. The high pressures involved mean that the .300 Lapua Magnum should only be chambered in rifles that are specifically designed for extremely high-powered cartridges. Chambering such powerful super magnum cartridges in rifles intended for normal magnum rifle cartridges and using P_max loads can cause serious or fatal injury to the shooter and bystanders. A rifle that theoretically could safely be chambered for the 94.5 mm long .300 Lapua Magnum is the bolt-action SAKO TRG-42. This rifle was designed for .338 Lapua Magnum cartridges and can handle cartridges up to 95 mm in overall length.

Additional information

The .300 Lapua Magnum’s main appeal is long-range shooting. Due to the large case capacity in relation to the bore diameter (known as

overbore Overbore cartridges are those with a relatively large case volume or case capacity, coupled with a relatively small diameter bullet. The case volume or case capacity and barrel bore area can be mathematically related to obtain a case volume to bore ...

) the .300 Lapua Magnum is harsh on barrels and typically wears them out in 1,000 to 1,500 rounds. Thorough cleaning and avoiding numerous consecutive shots help to minimize barrel wear. This makes this cartridge impractical for most competition and professional long-range shooters, such as military

sniper A sniper is a military or paramilitary marksman who engages targets from positions of concealment or at distances exceeding the target's detection capabilities. Snipers generally have specialized training and are equipped with telescopic si ...

s, who tend to fire many rounds in practice to acquire and maintain expert long-range marksmanship. The 2008 Vihtavuori reloading guide states that, when loaded with heavy .30 caliber bullets and fired out of a 690 mm (27 in) barrel, the .300 Lapua Magnum has lower muzzle energy compared to the .338 Lapua Magnum. The belted .30-378 Weatherby Magnum cartridge, introduced in 1996, and the rebated-rim .300 Remington Ultra Magnum cartridge, introduced in 1999, are probably the closest commercially available ballistic equivalents of the .300 Lapua Magnum.

References

* Cartridge Dimensions -
.300 Lapua Magnum cartridge dimensions at Steves Pages
* C.I.P. CD-ROM edition 2003 * C.I.P. decisions, texts and tables
free current C.I.P. CD-ROM version download (ZIP and RAR format)

External links

* QuickLOAD internal ballistics predictor computer program for fire arms
VihtaVuori Reloading Guide, 2002

* ttps://bobp.cip-bobp.org/uploads/tdcc/tab-i/tabical-en-page116.pdf C.I.P. TDCC sheet 300 Lapua Mag. {{DEFAULTSORT:300 Lapua Magnum Pistol and rifle cartridges Magnum rifle cartridges Nammo Lapua cartridges

History

Cartridge dimensions

Additional information

See also

References

External links