7.62 UKM
Encyclopedia
The 7.62 UKM is a specialized rimless
bottlenecked centerfire cartridge
developed for long-range rifle
s. The commercially successful .338 Lapua Magnum cartridge has functioned as the parent case for the 7.62 UKM, which is essentially a necked-down shortened 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 high muzzle velocities.
) certified in 2002, so it is an officially registered and sanctioned member of the Finnish "family" of super magnum rifle cartridges. The 7.62 UKM is not commercially available today and currently (2008) 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.
(90 grains
) H2O cartridge case capacity. The exterior shape of the Lapua Magnum case was designed to promote reliable case feeding and extraction in bolt action rifles and machineguns alike, under extreme conditions.
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. guidelines the 7.62 UKM case can handle up to 470 MPa (68,167 psi) 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 for rifles very high maximum allowed chamber pressure level indicates that the cases of the .300 and .338 Lapua Magnum and 7.62 UKM 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 7.62 UKM 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.
The American .300 Dakota proprietary cartridge, based on the .404 Jeffery
case, is probably the closest currently (2008) commercially available ballistic twin of the 7.62 UKM. The .300 Dakota is however a rebated rim
cartridge.
Rim (firearms)
A rim is an external flange that is machined, cast, molded, stamped or pressed around the bottom of a firearms cartridge. The rim may serve a number of purposes, the most common being as the place for the extractor to engage...
bottlenecked centerfire cartridge
Cartridge (firearms)
A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...
developed for long-range rifle
Rifle
A rifle is a firearm designed to be fired from the shoulder, with a barrel that has a helical groove or pattern of grooves cut into the barrel walls. The raised areas of the rifling are called "lands," which make contact with the projectile , imparting spin around an axis corresponding to the...
s. The commercially successful .338 Lapua Magnum cartridge has functioned as the parent case for the 7.62 UKM, which is essentially a necked-down shortened 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
Bullet
A bullet is a projectile propelled by a firearm, sling, or air gun. Bullets do not normally contain explosives, but damage the intended target by impact and penetration...
s result in high muzzle velocities.
History
The 7.62 UKM was developed by Michael Uekötter and C.I.P. (Commission Internationale Permanente pour l'Epreuve des Armes à Feu PortativesCommission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives
The Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives is an international organisation whose members are 14 states, mainly European....
) certified in 2002, so it is an officially registered and sanctioned member of the Finnish "family" of super magnum rifle cartridges. The 7.62 UKM is not commercially available today and currently (2008) 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
Handloading
Handloading or reloading is the process of loading firearm cartridges or shotgun shells by assembling the individual components , rather than purchasing completely assembled, factory-loaded cartridges...
it with .30 calibre bullets.
Cartridge dimensions
The 7.62 UKM has a 5.84 mlLitre
pic|200px|right|thumb|One litre is equivalent to this cubeEach side is 10 cm1 litre water = 1 kilogram water The litre is a metric system unit of volume equal to 1 cubic decimetre , to 1,000 cubic centimetres , and to 1/1,000 cubic metre...
(90 grains
Grain (measure)
A grain is a unit of measurement of mass that is nominally based upon the mass of a single seed of a cereal. From the Bronze Age into the Renaissance the average masses of wheat and barley grains were part of the legal definition of units of mass. However, there is no evidence of any country ever...
) H2O cartridge case capacity. The exterior shape of the Lapua Magnum case was designed to promote reliable case feeding and extraction in bolt action rifles and machineguns alike, under extreme conditions.
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
Rifling
Rifling is the process of making helical grooves in the barrel of a gun or firearm, which imparts a spin to a projectile around its long axis...
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
Percussion cap
The percussion cap, introduced around 1830, was the crucial invention that enabled muzzleloading firearms to fire reliably in any weather.Before this development, firearms used flintlock ignition systems which produced flint-on-steel sparks to ignite a pan of priming powder and thereby fire the...
is large rifle magnum.
According to the official C.I.P. guidelines the 7.62 UKM case can handle up to 470 MPa (68,167 psi) 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 for rifles very high maximum allowed chamber pressure level indicates that the cases of the .300 and .338 Lapua Magnum and 7.62 UKM 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 7.62 UKM should only be chambered in rifles that are capable of handling such large and fierce cartridges and thus high bolt thrust
Bolt thrust
Bolt thrust or breech pressure is a term used in internal ballistics and firearms that describes the amount of rearward force exerted by the propellant gases on the bolt or breech of a firearm action or breech when a projectile is fired...
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.
Additional information
The 7.62 UKM’s main appeal is long-range shooting. Due to the large case capacity in relation to the 7.62 mm (.308 inch) calibre bore size the 7.62 UKM is harsh on barrels. The 7.62 UKM typically wears out a rifle barrel in 750 to 1500 rounds. A lot of thorough barrel cleaning (after every 5 to 10 shots) and carefully avoiding long strings of shots help to minimize barrel wear.The American .300 Dakota proprietary cartridge, based on the .404 Jeffery
.404 Jeffery
The .404 Jeffery is a large caliber, rimless cartridge designed for large, dangerous game, such as the big five of Africa. Other names for this cartridge include .404 Jeffery Rimless, .404 Rimless Nitro Express, and 10.75 × 73 mm...
case, is probably the closest currently (2008) commercially available ballistic twin of the 7.62 UKM. The .300 Dakota is however a rebated rim
Rim (firearms)
A rim is an external flange that is machined, cast, molded, stamped or pressed around the bottom of a firearms cartridge. The rim may serve a number of purposes, the most common being as the place for the extractor to engage...
cartridge.
See also
- List of rifle cartridges
- 7 mm caliber7 mm caliberThis article lists firearm cartridges which have a bullet in the to caliber range.*Length refers to the cartridge case length.*OAL refers to the overall length of the cartridge....
- .300 Lapua Magnum.300 Lapua MagnumThe .300 Lapua Magnum is a specialized rimless bottlenecked centerfire cartridge developed for long-range rifles. 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...
- .338 Lapua Magnum
External links and sources
- QuickLOADQuickLOADQuickLOAD is an internal ballistics predictor computer program for fire arms.For computations apart from other parameters* the cartridge* the used projectile * the gunbarrel length* the cartridge overall length* the used propellant...
internal ballistics predictor computer program for fire arms