Test barrel length: 650 mm (25.59 in) Source: RWS / RUAG Ammotech 
The 9.3 x 64 Brenneke (also unofficially known as the 9.3 x 64) is a rimless bottlenecked centerfirecartridge developed for big game hunting. As is customary in European cartridges the 9.3 denotes the 9.3 mm bullet calibre and the 64 denotes the 64 mm case length. The 9.3 x 64 Brenneke can easily be chambered in standard sized Mauser 98bolt action rifles.
One of the most successful cartridge designs of the famous German gun and ammunition designer Wilhelm Brenneke (1865–1951) was the 9.3 x 64 Brenneke. He designed this cartridge de novo (the 9.3 x 64 Brenneke has no other cartridge as parent case) and introduced it commercially in 1927. This big game cartridge is the most powerful cartridge he designed. The 9.3 x 64 Brenneke was designed to have the largest possible case capacity without any shape or dimensional drawbacks that would hamper its chambering and perfect functioning in MauserGewehr 98 rifles that were then standard issue in the German military.
The widespread availability of standard size Mauser 98 rifles in central Europe and the fact that the .375 Holland & Holland Magnum cartridge and its necked down version the .300 Holland & Holland Magnum with approximately 72.4 mm case length were too long to fit in standard sized Mauser 98 bolt action rifles made the shorter 9.3 x 64 Brenneke an interesting chambering option for European big game hunters.
Brenneke introduced the 9.3 x 64 Brenneke with a 19.65 gram (303 gr) Torpedo Ideal Geschoss (TIG – Torpedo Ideal projectile) designed for big game and a 17 gram (262 gr) jacketed bullet with lead, bronze or a copper tip for smaller game. Later a special TIG with a bronze tip and a full metal jacket bullet where added for thick skinned dangerous game. After that Brenneke developed a 19 gram (293 gr) Torpedo Universal Geschoss (TUG – Torpedo Universal projectile) with a lead tip that is still produced.
The 9.3 x 64 Brenneke ballistic performance is on par with the .375 Holland & Holland Magnum whilst being smaller and using less propellant, making it a more modern efficient design.
With the official certification of the 6.5 x 63 Messner Magnum this German 64 mm "family" of magnum rifle cartridges that all share the same basic cartridge case got expanded 71 years later.
The cartridges in this German 64 mm cartridge "family" are, in the order of development:
The 9.3 x 64 Brenneke has 5.71 ml (88 grains) H2O cartridge case capacity. A rare feature of this German rimless bottlenecked centerfire cartridge design is that it has a slightly rebated rim (P1 - R1 = 0.28 mm). A sign of the era in which the 9.3 x 64 Brenneke 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.
9.3 x 64 Brenneke maximum C.I.P. cartridge dimensions. All sizes in millimetres (mm).
Americans would define the shoulder angle at alpha/2 ≈ 17.49 degrees. The common riflingtwist rate for this cartridge is 360 mm (1 in 14.17 in), 4 grooves, Ø lands = 9.00 mm, Ø grooves = 9.28 mm, land width = 4.60 mm and the primer type is large rifle magnum.
The .375 Holland & Holland Magnum cartridge is probably the closest ballistic twin of the 9.3 x 64 Brenneke. When compared to the 9.3 x 64 Brenneke the .375 Holland & Holland Magnum has a slightly larger calibre and it is a belted cartridge
A powerful cartridge like the 9.3 x 64 Brenneke has its drawbacks. Like every other big game cartridge it presents a stout recoil. An appropriate fitting stock and an effective muzzle brake will help to reduce recoil induced problems. An advantage of the short stocky 9.3 x 64 Brenneke is that it can be chambered in standard sized bolt-action rifles.
German big game hunters often use 9.3 x 64 Brenneke rifles in Africa for hunting plains game and Big Five game, where British or American hunters would choose the .375 Holland & Holland Magnum or similar cartridges. As a pure civil cartridge it can be used in countries which ban civil use of former or current military ammunition. The 9.3 x 64 Brenneke has a good accuracy reputation i.e. it is not hard to develop or find loads that will shoot 1 MoA or better out of decent standard mass produced rifles.
There are not many factory loads available. After WWII only the 19 gram (293 gr) TUG was produced by the Brenneke Company and later a 18.5 gram (285 gr) round nose and a 16 gram Torpedo Optimal Geschoss (TOG – Torpedeo Optimal projectile) bullet were added to the Brenneke factory load pallet. With these loads the 9.3 x 64 Brenneke gained a good reputation amongst German hunters on their big game safaris.
The German ammunition manufacturer RWS also offers 2 factory loads. In America A-Square offers the 9.3 x 64 Brenneke loaded with 18,5 gram (285 gr) lion load, 18,5 gram (285 gr) dead tough and 18,5 gram (285 gr) monolithic solid bullets.
Due to its good field reputation, efficiency and flexibility, the 9.3 x 64 Brenneke is often used by reloaders. They have used this cartridge extensively to create powerful loads by handloading. Whilst staying within the 440 MPa C.I.P. limit a 9.3 x 64 Brenneke rifle with a 610 mm (24 in) long barrel and appropriate modern gunpowder can be handloaded to propel bullets ranging from 5.83 – 20.74 gram (90 – 320 gr) for all kinds of hunting.
Reloaders realized that bullets with different characteristics can be utilized to produce varying effects on game. They also realized that from 8 mm calibre upwards the rise of sectional density and penetrating capability of practical spin stabilized rifle bullets (bullets up to 5 to 5.5 calibres in length) tends to flatten out .
This means that loaded with light, short and soft nosed 9.3 mm bullets the 9.3 x 64 Brenneke can be used on remarkable small game. Loaded with heavy, long and hard (solid copper) bullets the 9.3 x 64 Brenneke offers enough weight and speed derived power to penetrate heavy and dangerous game. The 9.3 x 64 Brenneke is suitable for hunting any game animal on the planet, though certain sub-Saharan Africa countries have a 9.53 mm (.375 in) minimum calibre rule for hunting Big Five game - i.e. leopard, lion, cape buffalo, rhino and elephant. In the growing number countries, where the 9.3 x 64 Brenneke can be legally applied, it is used successfully for hunting elephant making it a flexible safari cartridge.
The 9.3 x 64 Brenneke case has functioned as the parent case for the 6.5 x 63 Messner Magnum, which is essentially a 6.5 mm (.264 in) necked-down version of the 9.3 x 64. The wildcat status of the 6.5 x 63 Messner Magnum ended in 2002 when it got C.I.P. certified and became an officially registered and sanctioned member of the German 64 mm "family" of magnum rifle cartridges.
The 6.5 x 63 Messner Magnum has 5.42 ml (83.5 grains) water cartridge case capacity.
6.5 x 63 Messner Magnum maximum C.I.P. cartridge dimensions. All sizes in millimetres (mm).
Americans would define the shoulder angle at alpha/2 = 29 degrees. The common rifling twist rate for this cartridge is 200 mm (1 in 7.87 in), 6 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. guidelines the 6.5 x 63 Messner Magnum case can handle up to 440 MPa (63,816 psi) piezo pressure.
The idea behind the 6.5 x 63 Messner Magnum was to develop a very powerful 6.5 mm long range hunting cartridge that achieves very high muzzle velocities out of relatively short 600 mm (23.62 in) long rifle barrels. The developer, Mr. Joseph Messner from France, chose the 9.3 x 64 Brenneke as parent case, since it offers enough case capacity and a competent gunsmith can relatively easy rechamber a standard Mauser 98 or any other bolt action rifle to accept 9.3 x 64 Brenneke based cartridges.
Due to the large case capacity in relation to the 6.5 mm (.264 inch) calibre bore size the 6.5 x 63 Messner Magnum is very harsh on barrels. It 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.
The German 6.5 x 68 cartridge introduced in 1939 and the American .264 Winchester Magnum cartridge introduced in 1959 are probably the closest ballistic twins of the 6.5 x 63 Messner Magnum.
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, SAAMI (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. Because the 9.3 x 64 Brenneke offers a 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.
An example of a 9.3 x 64 Brenneke based wildcat is the 8 mm Mázon. This is essentially a 8 mm (.323 in) necked-down version of the 9.3 x 64.