.450 Rigby
| .450 Rigby Rimless | ||||||||
|---|---|---|---|---|---|---|---|---|
| Type | Rifle | |||||||
| Place of origin |  UK | |||||||
| Production history | ||||||||
| Designer | Paul Roberts | |||||||
| Designed | 1994 | |||||||
| Manufacturer | John Rigby & Co. | |||||||
| Produced | 1995 | |||||||
| Variants | .450 Dakota | |||||||
| Specifications | ||||||||
| Parent case | .416 Rigby Rimless | |||||||
| Case type | Rimless bottlenecked | |||||||
| Bullet diameter | .458 in (11.6 mm) | |||||||
| Neck diameter | .487 in (12.4 mm) | |||||||
| Shoulder diameter | .571 in (14.5 mm) | |||||||
| Base diameter | .589 in (15.0 mm) | |||||||
| Rim diameter | .590 in (15.0 mm) | |||||||
| Rim thickness | .065 in (1.7 mm) | |||||||
| Case length | 2.894 in (73.5 mm) | |||||||
| Overall length | 3.750 in (95.3 mm) | |||||||
| Case capacity | 136 gr H2O (8.8 cm3) | |||||||
| Primer type | Large rifle (magnum) | |||||||
| Maximum pressure | 58,000 psi (400 MPa) | |||||||
| Ballistic performance | ||||||||
| ||||||||
| Test barrel length: 26 Source(s): Kynoch/Kynamco | ||||||||
The .450 Rigby Magnum Rimless better known simply as the .450 Rigby is a .45 caliber (11.6 mm) rimless, bottlenecked cartridge intended for the hunting of heavy dangerous game. The cartridge is based on the .416 Rigby necked up to accept a .458-inch (11.6 mm) bullet. The cartridge is intended for use in magazine rifles.[1] The cartridge should not be confused with the .450 Rigby Nitro Express which is a rimmed cartridge intended for double rifles.
History
In 1993 Paul Roberts (at the time proprietor of John Rigby & Company) was on an elephant hunt in the Zambezi Valley. Both he and his professional hunter, Joseph Wright, were armed with .416 Rigby rifles for the occation. An elephant was located and then shot in the lungs, but due to a misjudgment in distance several more rounds were required to finally bring down the elephant.[2]
After this experience, Paul Roberts felt that a cartridge with a greater bullet weight of a larger caliber would have been more effective in that situation. Once Paul Roberts returned to the United Kingdom he necked up the .416 Rigby case to .458 caliber. The new cartridge fired the 480-grain (31 g) of the .450 Nitro Express cartridge at a velocity of 2,378 ft/s (725 m/s) from a 25.5-inch (650 mm) barrel. The new cartridge was given named the .450 Rigby Magnum Rimless in 1994.[2] The cartridge was put into production in 1995. The John Rigby & Company was building the .416 Rigby rifles on the 98 Magnum Mauser action. Since the .416 Rigby and the .450 Rigby use basically the same case, building rifles for the .450 Rigby was rather simple requiring only a chamber with a modification made in the collar area and a .458 caliber (11.43 mm) barrel.
Cartridge Specifications
The .416 Rigby which was designed by the John Rigby & Co. in 1911 was one of the most voluminous cartridge cases designed for magazine rifles. By today’s standards it is a rather inefficient cartridge when burning smokeless powder to achieve the desired velocity with a given bullet weight. This is due to the large capacity case which was designed for use with cordite rather than smokeless powder. Consequently, the .450 Rigby, which uses virtually the same case as the .416 Rigby in turn suffers the same inefficiencies. The .458 Lott will use about 81.0 gr (5.25 g) of a powder to reach 2,350 ft/s (720 m/s) with a 500 gr (32 g) bullet while the .450 Rigby will use about 99.0 gr (6.42 g) to reach the same velocity with the same bullet. This works out to be about 22% more powder for equal velocity with the same bullet weight. This is due to the larger capacity of the .450 Rigby case which has a case capacity of 133.1 gr. of water (8.64 cm3). However, since the case is voluminous, it is able to turn out this performance at lower pressure levels which is considered beneficial and adding a greater safety margin in a dangerous game rifle cartridge intended for use in the tropics.
The .450 Rigby dimensions and specifications are standardized and governed by the CIP.
- CIP compliant .450 Rigby Magnum Rimless cartridge schematic: All dimensions in inches [millimeters].
The CIP recommends a bore diameter of 11.43-millimetre (0.450 in) and a groove diameter of 11.63-millimetre (0.458 in). Barrel will have a 6 grove rifling contour with a twist rate of one revolution in 420 mm (17 in) and a groove width of 3.60-millimetre (0.142 in). CIP specifies a maximum pressure of 4,000 bar (58,000 psi).
Performance
Unlike many of the modern .458 caliber dangerous game cartridges like the .458 Winchester, .458 Lott or the .460 Weatherby Magnum, the .450 Rigby was designed to operate at more moderate pressures. Maximum pressure limits enforced by CIP is given at 4,000 bar (58,000 psi). At these pressures, the cartridge easily reaches the intended 2,300–2,400 ft/s (700–730 m/s) with the 500-grain (32 g) bullet.[2] The lower pressures provide greater operational reliability in tropical environments where the cartridge is intended for use. Heat can cause higher than normal pressures which can lead to difficulty in extracting the spent case. In a dangerous game hunting situation such failures can result in injury or possibly a fatality.
Handloaders can take advantage of the wide range of .458 caliber (11.6 mm) bullets available. Acceptable bullets weight range from 300-grain (19 g) to 600-grain (39 g). The 500-grain (32 g) bullet can easily reach 2,500 ft/s (760 m/s) and staying within the pressure limitation imposed on the cartridge.[3]
Sporting Use
The .450 Rigby was designed primarily to take heavy, thick skinned, dangerous game species. When hunting these game species a bullet of a tough construction is required especially at the velocities the .450 Rigby is capable of attaining. Even heavy for caliber bullets like the 600-grain (39 g) may fail to perform adequately if lightly constructed. The bullets which are more lightly constructed can be used for larger non-dangerous game species similar to kudu or eland.[3]
.450 Dakota
The .450 Dakota is a variation on the design of the .450 Rigby but predates the latter cartridge by a few years. The Dakota cartridge was designed by Don Allen and is like the .450 Rigby based on the .416 Rigby case. While dimensions of the cartridges are similar they are not identical and are not interchangeable. The performance of both cartridges are almost identical. The .450 Dakota, however, is is loaded to a somewhat higher pressure of 59,500 psi (4,100 bar).
References
- ^ Barnes, Frank C. (2006) [1965]. Skinner, Stan (ed.). Cartridges of the World (11th Edition ed.). Gun Digest Books. p. 399. ISBN 0-89689-297-2.
{{cite book}}:|edition=has extra text (help); More than one of|pages=and|page=specified (help) - ^ a b c Haley, Charlie. "The .450 Rigby Magnum Rimless:-A Look At the Cartridge and a Rifle" (PDF). African Hunter. 11 (1). Harare, Zimbabwe: Mag-Set Publications: 45–48. Retrieved 28 September 2010.
- ^ a b Stumpfe, Karl (2004). "Reloading the .450 Rigby Rimless Magnum" (PDF). man Magnum. South Africa: South African Man Pty Ltd: 80–83. Retrieved 29 September 2010.
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