6.5x68mm
Encyclopedia
The 6.5x68mm rimless
bottlenecked rifle
cartridge
(also incorrectly known as the 6.5x68mm RWS, 6.5x68mm Schüler or the 6.5x68mm Von Hofe Express) and its sister cartridge
the 8x68mm S
were developed in the 1930s by Mr. Schüler from the August Schüler Waffenfabrik, Suhl, Germany as magnum hunting cartridges that would just fit and function in standard sized Mauser 98 bolt action rifles. This is one of the early examples where a de novo rifle cartridge
(the 6.5x68mm and 8x68mm S have no other cartridge as parent case) was developed by a gunsmith
to fit a specific popular and widespread type of rifle.
manufacturer RWS (Rheinisch-Westfälischen Sprengstoff factories) introduced both cartridges commercially in the spring of 1939. With the official certification of the .375 Hölderlin this German 68 mm "family" of magnum rifle cartridges that all share the same basic cartridge case got expanded 68 years later.
The cartridges in this German 68 mm cartridge "family" are, in the order of development:
The M 98 bolt actions of standard military Mauser 98 rifles have to be adapted by a competent gunsmith
to function properly with these magnum cartridges since they are longer and the cases have a larger diameter than the 8x57mm service cartridges. In properly adapted standard military Gewehr 98
or Karabiner 98k
service rifles the large 6.5x68mm cartridges are however praised for very smooth and reliable feeding.
The widespread availability of standard size Mauser 98 rifles and the fact that the .375 H&H Magnum
cartridge and its necked down version the .300 H&H Magnum
with approximately 72.4 mm case length were too long to fit in standard sized Mauser 98 bolt action rifles makes the shorter 6.5x68mm, 8x68mm S and .375 Hölderlin interesting chambering options.
World War II
spoiled the commercial introduction and spread of the 6.5x68mm. The cartridge became popular after World War II due to its high performance and flat trajectory
, when German hunters were allowed again to own and hunt with full bore rifles. The 6.5x68mm's performance also made it that hunters who had problems with handling magnum cartridge recoil stepped down to less powerful but adequate medium cartridges like the 6.5x57mm, 7.92x57 mm Mauser, 7x64mm
(Brenneke) or .30-06 Springfield
(also known as the 7.62x63mm in metric countries). Recoil sensitive shooters can fit an efficient muzzle brake
to significantly reduce the amount of recoil. With the help of a muzzle brake, the 6.5x68mm's recoil is reduced to tolerable levels.
(86 grains
) H2O cartridge case capacity for the 6.5x68mm. A rare feature of this German rimless bottlenecked centerfire cartridge design is that it has a slightly rebated rim (P1-R1 = 0.3 mm). A sign of the era in which the 6.5x68mm was developed are the gently sloped shoulders. The exterior shape of the case was designed to promote reliable case feeding and extraction in bolt action rifles, under extreme conditions.
6.5x68mm maximum C.I.P. cartridge dimensions. All sizes in millimetres (mm).
Americans would define the shoulder angle at alpha/2 ≈ 14.53 degrees. The common rifling
twist rate for this cartridge is 250 mm (1 in 9.84 in), 4 grooves, Ø lands = 6.45 mm, Ø grooves = 6.70 mm, land width = 3.50 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
) guidelines the 6.5x68mm case can handle up to 440 MPa (63817 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.
When the 6.5x68mm was introduced in 1939 it probably held the title of fastest production cartridge on the market. Nowadays there are commercial cartridges on the market which offer even higher muzzle velocities.
The American .264 Winchester Magnum
cartridge introduced in 1959 and the French 6.5x63mm Messner Magnum are probably the closest ballistic twins of the 6.5x68mm.
mountain range
. The 6.5x68mm as a pure civil cartridge can be used in countries which ban civil use of former or current military ammunition.
Since there are not many factory loads available (RWS offers only 2 factory loads) and due to its good field reputation, the 6.5 x 68 is often used by reloaders
. They have used this cartridge extensively to create powerful loads by handloading
.
Factory rifles in 6.5x68mm normally have 250 mm to 280 mm (1 in 9.8 to 11 inch) twist rates, which are too long to adequately stabilize modern long heavy 6.5 mm bullets. This slow twist rate was chosen since the bullet jackets used in the 1930s were not strong enough to cope with the forces generated by the magnum muzzle velocities of the 6.5x68mm. The traditional 6.5x68mm twists nowadays inhibits its potential. To make the 6.5x68mm an awesome long-range cartridge, rifle barrels with a 200 mm to 230 mm (1 in 7.9 to 9 inch) twist rate are a better choice. Due to the large case capacity in relation to the 6.5 mm (.264 inch) caliber bore size the 6.5x68mm is very harsh on barrels. The 6.5x68mm typically wears out a rifle barrel in 500 to 1000 rounds. A lot of thorough barrel cleaning (after every 5 shots) and carefully avoiding long strings of shots help to minimize barrel wear. This makes this cartridge unpractical for most competition shooters who tend to fire a lot of rounds in practice to acquire and maintain expert long-range marksmanship.
Reloaders use the 6.5x68mm as a Jack of all trades long-range cartridge on all European game from fox
, roe deer
and chamois
upwards to the big European game like red deer
and moose
. These people realized that bullets with different characteristics can be utilized to produce varying effects on game. As with all 6.5 mm cartridges, the big game hunting bullets used in the 6.5x68mm have comparatively high sectional densities
for good penetration on suitable size game animals.
(Sporting Arms and Ammunition Manufacturers’ Institute) are generally known as wildcats
. By blowing out standard factory cases the wildcatter generally hopes to gain extra muzzle velocity by increasing the case capacity of the factory parent cartridge case by a few percent. Practically there can be some muzzle velocity gained by this method, but the measured results between parent cartridges and their 'improved' wildcat offspring is often marginal. Besides changing the shape and internal volume of the parent cartridge case, wildcatters also can change the original caliber. A reason to change the original caliber can be to comply with a minimal permitted caliber or bullet weight for the legal hunting of certain species of game.
Wildcats are not governed by C.I.P. or SAAMI rules so wildcatters can capitalize the achievable high operating pressures. It is often reported that modern 68 mm RWS brass can tolerate up to 500 MPa (72519 psi) piezo pressure. Because the 6.5x68mm offers an exceptional sturdy, pressure resistant cartridge case that can relatively easily be reloaded with primers, powder and bullets and hence be reused several times it has become quite popular amongst wildcatters. With the German 68 mm magnum cartridge case as parent case wildcatters have created .25x68, .270x68, 7x68mm, .30x68, .338x68, .375x68 or .416x68 variants.
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 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...
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...
(also incorrectly known as the 6.5x68mm RWS, 6.5x68mm Schüler or the 6.5x68mm Von Hofe Express) and its sister 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...
the 8x68mm S
8x68mm S
The 8x68mm S rimless bottlenecked rifle cartridge and its necked down sister cartridge the 6.5x68mm were developed in the 1930s by Mr...
were developed in the 1930s by Mr. Schüler from the August Schüler Waffenfabrik, Suhl, Germany as magnum hunting cartridges that would just fit and function in standard sized Mauser 98 bolt action rifles. This is one of the early examples where a de novo rifle 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...
(the 6.5x68mm and 8x68mm S have no other cartridge as parent case) was developed by a gunsmith
Gunsmith
A gunsmith is a person who repairs, modifies, designs, or builds firearms. This occupation is different from an armorer. The armorer primarily maintains weapons and limited repairs involving parts replacement and possibly work involving accurization...
to fit a specific popular and widespread type of rifle.
History
The German ammunitionAmmunition
Ammunition is a generic term derived from the French language la munition which embraced all material used for war , but which in time came to refer specifically to gunpowder and artillery. The collective term for all types of ammunition is munitions...
manufacturer RWS (Rheinisch-Westfälischen Sprengstoff factories) introduced both cartridges commercially in the spring of 1939. With the official certification of the .375 Hölderlin this German 68 mm "family" of magnum rifle cartridges that all share the same basic cartridge case got expanded 68 years later.
The cartridges in this German 68 mm cartridge "family" are, in the order of development:
- 8x68mm S8x68mm SThe 8x68mm S rimless bottlenecked rifle cartridge and its necked down sister cartridge the 6.5x68mm were developed in the 1930s by Mr...
(1939) - 6.5x68mm (1939)
- .375 Hölderlin (2007)
The M 98 bolt actions of standard military Mauser 98 rifles have to be adapted by a competent gunsmith
Gunsmith
A gunsmith is a person who repairs, modifies, designs, or builds firearms. This occupation is different from an armorer. The armorer primarily maintains weapons and limited repairs involving parts replacement and possibly work involving accurization...
to function properly with these magnum cartridges since they are longer and the cases have a larger diameter than the 8x57mm service cartridges. In properly adapted standard military Gewehr 98
Gewehr 98
The Gewehr 98 is a German bolt action Mauser rifle firing the 8x57mm cartridge from a 5 round internal clip-loaded magazine that was the German service rifle from 1898 to 1935, when it was replaced by the Karabiner 98k. It was hence the main rifle of the German infantry during World War I...
or Karabiner 98k
Karabiner 98k
The Karabiner 98 Kurz was a bolt action rifle chambered for the 8x57mm IS/7.92×57mm IS cartridge that was adopted as the standard service rifle in 1935 by the German Wehrmacht. It was one of the final developments in the long line of Mauser military rifles...
service rifles the large 6.5x68mm cartridges are however praised for very smooth and reliable feeding.
The widespread availability of standard size Mauser 98 rifles and the fact that the .375 H&H Magnum
.375 H&H Magnum
The .375 Holland & Holland Magnum is a powerful rifle round and one of the best-known and most popular medium-bore cartridges in the world. The .375 H&H was only the second cartridge ever to feature a belt, now common among magnum rounds. A popular misconception is that the belt is for headspace,...
cartridge and its necked down version the .300 H&H Magnum
.300 H&H Magnum
The .300 H&H Magnum Cartridge was introduced by the British company Holland & Holland as the Super-Thirty in June, 1925. The case was belted like the .375 H&H Magnum, and is based on the same case, as also is the .244 H&H Magnum. The belt is for headspace as the cases' shoulders have a narrow...
with approximately 72.4 mm case length were too long to fit in standard sized Mauser 98 bolt action rifles makes the shorter 6.5x68mm, 8x68mm S and .375 Hölderlin interesting chambering options.
World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
spoiled the commercial introduction and spread of the 6.5x68mm. The cartridge became popular after World War II due to its high performance and flat trajectory
Trajectory
A trajectory is the path that a moving object follows through space as a function of time. The object might be a projectile or a satellite, for example. It thus includes the meaning of orbit—the path of a planet, an asteroid or a comet as it travels around a central mass...
, when German hunters were allowed again to own and hunt with full bore rifles. The 6.5x68mm's performance also made it that hunters who had problems with handling magnum cartridge recoil stepped down to less powerful but adequate medium cartridges like the 6.5x57mm, 7.92x57 mm Mauser, 7x64mm
7x64mm
The 7x64mm is a rimless bottlenecked centerfire cartridge developed for hunting. As is customary in European cartridges the 7 denotes the 7 mm bullet caliber and the 64 denotes the case length...
(Brenneke) or .30-06 Springfield
.30-06 Springfield
The .30-06 Springfield cartridge or 7.62×63mm in metric notation, was introduced to the United States Army in 1906 and standardized, and was in use until the 1960s and early 1970s. It replaced the .30-03, 6 mm Lee Navy, and .30 US Army...
(also known as the 7.62x63mm in metric countries). Recoil sensitive shooters can fit an efficient muzzle brake
Muzzle brake
Muzzle brakes and recoil compensators are devices that are fitted to the muzzle of a firearm or cannon to redirect propellant gases with the effect of countering both recoil of the gun and unwanted rising of the barrel during rapid fire...
to significantly reduce the amount of recoil. With the help of a muzzle brake, the 6.5x68mm's recoil is reduced to tolerable levels.
Cartridge dimensions
Extremely thick brass results in 'only' 5.58 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...
(86 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 for the 6.5x68mm. A rare feature of this German rimless bottlenecked centerfire cartridge design is that it has a slightly rebated rim (P1-R1 = 0.3 mm). A sign of the era in which the 6.5x68mm was developed are the gently sloped shoulders. The exterior shape of the case was designed to promote reliable case feeding and extraction in bolt action rifles, under extreme conditions.
6.5x68mm maximum C.I.P. cartridge dimensions. All sizes in millimetres (mm).
Americans would define the shoulder angle at alpha/2 ≈ 14.53 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 250 mm (1 in 9.84 in), 4 grooves, Ø lands = 6.45 mm, Ø grooves = 6.70 mm, land width = 3.50 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. (Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives
Commission 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....
) guidelines the 6.5x68mm case can handle up to 440 MPa (63817 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.
When the 6.5x68mm was introduced in 1939 it probably held the title of fastest production cartridge on the market. Nowadays there are commercial cartridges on the market which offer even higher muzzle velocities.
The American .264 Winchester Magnum
.264 Winchester Magnum
The .264 Winchester Magnum is a belted, bottlenecked rifle cartridge. Apart from the .257 Weatherby Magnum, it is the smallest caliber factory cartridge which uses the standard length Holland & Holland belted magnum case...
cartridge introduced in 1959 and the French 6.5x63mm Messner Magnum are probably the closest ballistic twins of the 6.5x68mm.
The 6.5x68mm in field use
German and Austrian hunters use the powerful, high velocity 6.5x68mm for long-range hunting in mountainous terrain like the AlpsAlps
The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....
mountain range
Mountain range
A mountain range is a single, large mass consisting of a succession of mountains or narrowly spaced mountain ridges, with or without peaks, closely related in position, direction, formation, and age; a component part of a mountain system or of a mountain chain...
. The 6.5x68mm as a pure civil cartridge can be used in countries which ban civil use of former or current military ammunition.
Since there are not many factory loads available (RWS offers only 2 factory loads) and due to its good field reputation, the 6.5 x 68 is often used by reloaders
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...
. They have used this cartridge extensively to create powerful loads by 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...
.
Factory rifles in 6.5x68mm normally have 250 mm to 280 mm (1 in 9.8 to 11 inch) twist rates, which are too long to adequately stabilize modern long heavy 6.5 mm bullets. This slow twist rate was chosen since the bullet jackets used in the 1930s were not strong enough to cope with the forces generated by the magnum muzzle velocities of the 6.5x68mm. The traditional 6.5x68mm twists nowadays inhibits its potential. To make the 6.5x68mm an awesome long-range cartridge, rifle barrels with a 200 mm to 230 mm (1 in 7.9 to 9 inch) twist rate are a better choice. Due to the large case capacity in relation to the 6.5 mm (.264 inch) caliber bore size the 6.5x68mm is very harsh on barrels. The 6.5x68mm typically wears out a rifle barrel in 500 to 1000 rounds. A lot of thorough barrel cleaning (after every 5 shots) and carefully avoiding long strings of shots help to minimize barrel wear. This makes this cartridge unpractical for most competition shooters who tend to fire a lot of rounds in practice to acquire and maintain expert long-range marksmanship.
Reloaders use the 6.5x68mm as a Jack of all trades long-range cartridge on all European game from fox
Fox
Fox is a common name for many species of omnivorous mammals belonging to the Canidae family. Foxes are small to medium-sized canids , characterized by possessing a long narrow snout, and a bushy tail .Members of about 37 species are referred to as foxes, of which only 12 species actually belong to...
, roe deer
Roe Deer
The European Roe Deer , also known as the Western Roe Deer, chevreuil or just Roe Deer, is a Eurasian species of deer. It is relatively small, reddish and grey-brown, and well-adapted to cold environments. Roe Deer are widespread in Western Europe, from the Mediterranean to Scandinavia, and from...
and chamois
Chamois
The chamois, Rupicapra rupicapra, is a goat-antelope species native to mountains in Europe, including the Carpathian Mountains of Romania, the European Alps, the Tatra Mountains, the Balkans, parts of Turkey, and the Caucasus. The chamois has also been introduced to the South Island of New Zealand...
upwards to the big European game like red deer
Red Deer
The red deer is one of the largest deer species. Depending on taxonomy, the red deer inhabits most of Europe, the Caucasus Mountains region, Asia Minor, parts of western Asia, and central Asia. It also inhabits the Atlas Mountains region between Morocco and Tunisia in northwestern Africa, being...
and moose
Moose
The moose or Eurasian elk is the largest extant species in the deer family. Moose are distinguished by the palmate antlers of the males; other members of the family have antlers with a dendritic configuration...
. These people realized that bullets with different characteristics can be utilized to produce varying effects on game. As with all 6.5 mm cartridges, the big game hunting bullets used in the 6.5x68mm have comparatively high sectional densities
Sectional density
Sectional density is the ratio of an object's mass to its cross-sectional area. It conveys how well an object's mass is distributed to overcome resistance. For illustration, a needle can penetrate a target medium with less force than a coin of the same mass...
for good penetration on suitable size game animals.
The 6.5x68mm as parent case
Cartridges that are not officially registered with nor sanctioned by C.I.P. (Commission Internationale Permanente Pour L'Epreuve Des Armes A Feu Portative) or its American equivalent, SAAMISaami
Saami or SAAMI can stand for:*Sami people*Sami languages*Sporting Arms and Ammunition Manufacturers' Institute...
(Sporting Arms and Ammunition Manufacturers’ Institute) are generally known as wildcats
Wildcat cartridge
A wildcat cartridge, or wildcat, is a custom cartridge for which ammunition and firearms are not mass produced. These cartridges are often created in order to optimize a certain performance characteristic of an existing commercial cartridge.Developing and using wildcat cartridges does not...
. By blowing out standard factory cases the wildcatter generally hopes to gain extra muzzle velocity by increasing the case capacity of the factory parent cartridge case by a few percent. Practically there can be some muzzle velocity gained by this method, but the measured results between parent cartridges and their 'improved' wildcat offspring is often marginal. Besides changing the shape and internal volume of the parent cartridge case, wildcatters also can change the original caliber. A reason to change the original caliber can be to comply with a minimal permitted caliber or bullet weight for the legal hunting of certain species of game.
Wildcats are not governed by C.I.P. or SAAMI rules so wildcatters can capitalize the achievable high operating pressures. It is often reported that modern 68 mm RWS brass can tolerate up to 500 MPa (72519 psi) piezo pressure. Because the 6.5x68mm offers an exceptional sturdy, pressure resistant cartridge case that can relatively easily be reloaded with primers, powder and bullets and hence be reused several times it has become quite popular amongst wildcatters. With the German 68 mm magnum cartridge case as parent case wildcatters have created .25x68, .270x68, 7x68mm, .30x68, .338x68, .375x68 or .416x68 variants.