7.62 UKM

Infobox Firearm Cartridge
name=7.62 UKM


caption=
origin=Germany
type=Rifle
service=Never issued
used_by=
wars=
designer= Michael Uekötter
design_date=2002
manufacturer=
production_date=
number=small batch for C.I.P. registration
variants=
is_SI_specs=yes
parent=.338 Lapua Magnum
case_type=Rimless, bottleneck
bullet=7.82
neck=8.68
shoulder=14.06
base=14.91
rim_dia=14.93
rim_thick=1.52
case_length=57.00
length=79.00
case_capacity=5.84
rifling=250 mm (1-10")
primer=Large rifle magnum
max_pressure=470.00
max_cup=
is_SI_ballistics=
bw1=155
btype1=Laupa Scenar BTHP
vel1=3468
en1=4141
bw2=168
btype2=Sierra BTHP
vel2=3300
en2=4062
bw3=181
btype3=RWS TUG
vel3=3240
en3=4219
bw4=185
btype4=Berger BTHP
vel4=3149
en4=4073
bw5=220
btype5=Sierra BTHP
vel5=2982
en5=4345
test_barrel_length=27.5" (699 mm)
balsrc= [ [http://www.angelfire.com/ma/ZERMEL/762ukm.html The 7.62 UKM. A German 300 Magnum Wildcat Extraordinary.] and QuickLOAD (pressure limit of 470 MPa applied).] The 7.62 UKM (7.62 x 57 mm) 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 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 bullets 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 Portatives) 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.

Cartridge dimensions

The 7.62 UKM has a 5.84 ml (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. [ [http://www.cip-bp.org/index.php?id=tdcc-telechargement C.I.P. decisions, texts and tables - free current C.I.P. CD-ROM version download (ZIP and RAR format)] ]

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.

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 case, is probably the closest currently (2008) commercially available ballistic twin of the 7.62 UKM. [ [http://www.dakotaarms.com/dakota_cartridges.html Dakota Arms Cartridges] ] [ [http://www.cpcartridge.com/300dkaB.htm Conley Precision Cartridge 300 Dakota Ballistic Tables] ] The .300 Dakota is however a rebated rim cartridge.

ee also

* List of rifle cartridges
* 7 mm caliber
* .300 Lapua Magnum
* .338 Lapua Magnum

References

* C.I.P. CD-ROM edition 2003
* C.I.P. decisions, texts and tables ( [http://www.cip-bp.org/index.php?id=tdcc-telechargement free current C.I.P. CD-ROM version download (ZIP and RAR format)] )

External links and sources

*
* QuickLOAD internal ballistics predictor computer program for fire arms