The .460 Weatherby Magnum is a belted, bottlenecked rifle cartridge, developed by Roy Weatherby in 1957. The cartridge is based on the .378 Weatherby Magnum necked up to accept the bullet. The original .378 Weatherby Magnum parent case was inspired by the .416 Rigby. The .460 Weatherby Magnum was designed as an African dangerous game rifle cartridge for the hunting of heavy, thick skinned dangerous game.
Prior to the Weatherby's arrival, the .600 Nitro Express had been the most powerful cartridge but the .460 Weatherby Magnum eclipsed this, and was the world's most powerful commercially available sporting cartridge for 29 years until the advent of the .700 Nitro Express.Which was itself eclipsed in only five years by the 1993 introduction of the .577 Tyrannosaur.
The .460 launches a bullet at a chronographed velocity of from a barrel, measuring of muzzle energy.Weatherby Guide 12th Ed. 1962
Cartridge history Roy Weatherby had expected the .378 Weatherby Magnum to make some headway in the African continent but believed that his cartridge was being bypassed for low-velocity, big-bore cartridges by professional hunters who he felt were resistant to change. Furthermore, new regulations prohibiting the hunting of heavy, thick skinned, dangerous game with sub-.40 caliber (10.16 mm) cartridges were being enacted in some African countries. These regulations would essentially ban the use of all previous Weatherby cartridges for the hunting of elephant, African Cape buffalo and rhinoceros.
In response to these factors, Weatherby believed that it was necessary to provide hunters a Weatherby cartridge that could be used to hunt African dangerous game in the countries which had legislated against hunting with sub-.40 caliber rifles. He accomplished this by necking up the .378 Weatherby Magnum case to accept a .458 caliber bullet. He named the new cartridge the ".460 Weatherby Magnum". The first rifles for the .460 Weatherby Magnum were built on Brevex Magnum Mauser action.
However, Weatherby was not the first cartridge designer to neck up the .378 Weatherby Magnum to .45 caliber (11.6 mm). That distinction belongs to John Buhmiller, a gunsmith and hunter from Montana. Buhmiller named his cartridge the ".45 Weatherby". He had success with the cartridge in Africa shooting Cape buffalo and rogue elephants in 1956, a year before Weatherby began work on his own .45-caliber cartridge.
Norma Precision of Sweden was the first and only manufacturer of .460 Weatherby Magnum cases and ammunition which carried the Weatherby name and has done so under contract from Weatherby. During Weatherby's partnership with J.P. Sauer/Dynamit-Nobel, production at Norma ceased and shifted to RWS, a wholly owned subsidiary of Dynamit-Nobel. However, RWS did not tool up in time to produce the .460 Weatherby Magnum cartridge and in the end only produced substandard .300 Weatherby ammunition before production once again moved to Norma.
DuPont at one time shipped DuPont No. 4350 powder to Norma Projektilfabrik for the reloading of Weatherby ammunition. But some time later Norma was able to source a powder with similar burn characteristics locally which was used instead of DuPont's IMR 4350. Norma would later purchase the company and rename the powder Norma 204.
Design and specifications The .460 Weatherby Magnum is no longer considered a proprietary cartridge as the Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) established voluntary specifications for the cartridge in January 1994. The Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives (CIP) has also provided specifications for the cartridge to which all member states must comply when exporting, importing or manufacturing ammunition.
Cartridge design The .460 Weatherby Magnum case uses a necked up .378 Weatherby Magnum case. Although the .378 Weatherby Magnum case was inspired by the .416 Rigby case, it is considered a unique case which has gone on to serve as the parent cartridge of several high performance cartridges. The .460 Weatherby Magnum requires a case with the large propellant capacity necessary to propel a bullet at . To accomplish this design goal, the cartridge case has a capacity able to hold 141.1 gr. of water (9.17 cm3). Frequently the powder charges for the .460 Weatherby Magnum can weigh well in excess of ; in comparison a powder charge for the .458 Winchester Magnum rarely weighs over .Hornady Handbook of Cartridge Reloading 4th Ed.
The .460 Weatherby Magnum is designed to headspace on its belt. The close chamber tolerance of Weatherby rifles indicate that these rifles do indeed headspace on the belt rather than the shoulder, unlike most modern belted cartridges which headspace on the shoulder regardless of the belt; the few exceptions being the .375 H&H Magnum and the .300 H&H Magnum. SAAMI recommended chamber dimensional tolerance range does allow for the headspacing to take place on the shoulder if need be.
Cartridge dimensions and specifications
SAAMI compliant .460 Weatherby Magnum cartridge schematic: All dimensions in inches [millimeters].
Diagram reflects SAAMI dimensions for the .460 Weatherby Magnum. CIP dimensions for the r1 (inside shoulder radius), r2 (outside shoulder radius), L1 (height from base to shoulder), L2 (height from base to neck), S (shoulder angle intercepts the center line) and the α dimensional value (shoulder angle) conflict with SAAMI dimensions. This is due to how the L1 and L2 values are defined in relation to the centers of the r1 and r2 dimensional values by CIP. The following table provides the conflicting values provided by SAAMI and CIP.
{| class="wikitable" border="1" |+ Cartridge dimension and specification value conflicts between SAAMI and CIP |- | style="background: #eeeeee" width="200pt" | Dimension / specification | style="background: #eeeeee" width="180pt" | CIP dimension index | style="background: #eeeeee" width="180pt" | SAAMI value | style="background: #eeeeee" width="180pt" | CIP value |- | style="background: #eeeeee" | Body to shoulder radius || r1 || || |- | style="background: #eeeeee" | Neck to shoulder radius || r2 || || |- | style="background: #eeeeee" | Base to shoulder length || L1 || || |- | style="background: #eeeeee" | Base to neck length || L2 || || |- | style="background: #eeeeee" | Angle between shoulder || α || Does not provide || 56°15'56" |- | style="background: #eeeeee" | Length to shoulder vertex || S || Does not provide || |- | style="background: #eeeeee" | Pressure || Pmax || ||
Like all Weatherby cartridges, the .460 Weatherby Magnum cartridge has a double radius shoulder where the body and the neck are connected with a continuously curving shoulder; the curve of which reverses at the point of tangency. SAAMI defines the length to the shoulder as the demarcation point where the bottom of inside curvature radius (corresponding roughly to CIP's r1) of the shoulder begins and the length to the neck as where the outside curvature radius (approximating CIP's r2) meets the neck. However, CIP does not define the location of the centers of the r1 and r2 whereas SAAMI provides this as being in inline with the length to the shoulder (inside radius) and length to neck (outside radius). This is due to the CIP treatment of r1 and r2 values as fillet radii as they do with many other cartridges.
Chamber dimensions and specifications
SAAMI compliant .460 Weatherby Magnum chamber schematic: All dimensions in inches [millimeters].
SAAMI recommends a maximum chamber pressure rating of while CIP provides a maximum chamber pressure rating of .
Weatherby no longer provides a long leade (freebore) for the cartridge. Currently Weatherby provides of freebore for the .460 Weatherby in the Weatherby Mark V rifle. CIP recommends that rifling commence at from the case mouth reflecting the longer leade provided by Weatherby in the early 1960s. SAAMI recommends the present leade provided by Weatherby of .
Twist rate is given as 1 in 16 by Weatherby which would stabilize bullets up to and mono-metal bullets. Weatherby provides a six-groove contour No. 4 barrel for the .460 Weatherby Magnum. Ø land is given at and Ø groove is . The recommended land arc width by both SAAMI and CIP is .
Performance
The .460 Weatherby Magnum cartridge is very accurate despite its size. Weatherby guarantees a 1.5 MOA (44mm/100m) accuracy for this cartridge in a Weatherby rifle. Typically a full-metal-jacketed or monolithic solid type bullet will penetrate more than when impacting a dangerous game animal such as the Cape buffalo or African elephant. The .460 Weatherby Magnum has few peers for stopping dangerous African game.
Compared to its contemporaries, the 460 Weatherby Magnum has more energy at 150 yards than the .458 Winchester Magnum does at the muzzle and at 100 yards more energy than the .458 Lott with factory ammunition. The .460 Weatherby Magnum provides a significant step up in performance over other production .458 caliber (11.6 mm) cartridges. The increased performance is realized in terms of both remaining energy and extended range.
+ Comparison of the factory loadings of the .458 Winchester Magnum, 458 Lott and the .460 Weatherby Magnum Cartridge Criteria Muzzle .458 Winchester Magnum Hornady DGS Velocity Energy .458 Lott Hornady DGS Velocity Energy .460 Weatherby Magnum Hornady DGS Velocity Energy
The .460 Weatherby Magnum, like the .375 H&H Magnum, is a relatively flat shooting cartridge. The maximum point blank range (MPBR) for the Weatherby load is . The Weatherby factory ammunition has a maximum point blank range of . These trajectories compare well with those of the .375 H&H Magnum. At Hornady's Interlock .375 H&H Magnum's bullet drops while Hornady's DGX bullet drops . In contrast the .460 Weatherby Magnum's (B460450TSX) drops and the (H460500FJ) drops . The .460 Weatherby Magnum, however, averages over 75% greater energy than the .375 H&H Magnum.
Compared to the more popular .458 Winchester Magnum and the .458 Lott, the .460 Weatherby Magnum provides a flatter trajectory, dropping less than at when sighted in at with the 450 gr. Barnes TSX Weatherby ammunition. With the FMJ or RN Weatherby ammunition bullet drop is at the same range. The .458 Winchester Magnum and the .458 Lott have a and MPBR respectively in comparison. The FMJ or RN Weatherby ammunition shoot to the same point of impact, which is necessary in a dangerous game cartridge as hunters may need to switch from solids to soft round nose rounds depending on the circumstances and game being hunted. This is due to Weatherby's (Norma) factory loaded ammunition using Hornady's DGS and DGX bullets which have identical G1 ballistic coefficients of .295.
The ability of the .460 Weatherby to carry the energy and velocity required to take heavy, tough skinned dangerous game combined with the flatter trajectories it provides, gives the shooter the ability to take game species at longer ranges than its competition. The stand-off ability assures a greater margin of safety when hunting dangerous game species as the hunter need not get as close to the game as with other cartridges. Furthermore, this lessens the need to compensate for bullet drop and target size. However, for practical reasons, most dangerous game are shot at close ranges of less than .