.375 H&H Magnum

The .375 H&H Magnum is the result of competition between British rifle manufacturers to develop new cartridges to take advantage of the new smokeless powders. The 9.5×57mm Mannlicher–Schönauer cartridge had a major influence on British rifle manufacturers The introduction of the 9.3×62mm Mauser cartridge in 1905 had a profound and lasting influence on hunters in Africa. Compared to the British double rifles, the Mauser was a far less expensive rifle to manufacture and therefore cheaper to acquire. The double rifles gained little from industrialization whereas the Mauser rifles had gained from mass production due to contracts to produce military rifles for many countries. The result was cheap magazine rifles capable of firing one of the very best candidates for the all round hunting cartridge in Africa. The influence of Mauser's 98 action should not be understated; British gunmakers such as Rigby were purchasing the Mauser 98 actions for use in their own rifles with their own cartridges. The popularity of the 9.3×62mm Mauser was such that everyone from the German farmers in Africa to the white hunters from Europe discarded their previous doubles and less powerful magazine rifles and took to the 9.3×62mm. The 9.3×62mm demonstrated that it was adequate for everything from the dik-dik to the elephant and had acquired a reputation to match. The new cartridge was a proprietary design unlike the 9.3×62mm and was considerably longer than its German counterpart. While many .375 H&H rifles were built on the longer magnum Mauser actions, these actions were considerably more expensive and rarer than the standard actions. Standard actions could be used but required modifications to allow for flawless feeding and cycling of the .375 H&H Magnum cartridge. So while the .375 H&H provided considerable advantages over the 9.3×62mm, the significantly greater cost of the H&H rifles presented a roadblock to the adoption of the .375 H&H over the 9.3×62mm cartridge and remained for a time a less attractive option. At the end of World War I, Holland & Holland released the cartridge to the public for general trade. Also, new markets opened in America as more hunters sought to hunt in Africa. The .375 H&H was seen by many as the best medium bore dangerous game cartridge available for African safari hunting and which could be easily put to use for hunting large game in North America. Winchester was the first US gunmaker to produce rifles chambered for the cartridge and did so beginning in 1925. The end of World War II saw many gun makers turning to the civilian shooting market when war time contracts began running out. FN, Mauser, Remington and Winchester began turning out quality bolt-action rifles and with increasing number of sportsmen taking to Africa saw the .375 H&H increasing in popularity. A further boost in popularity came when African colonies enacted legislation stipulating that the or the be the minimum bullet diameter for dangerous game. The legislating away of sub minimum cartridges forced the users of these cartridges to pick up a cartridge which qualified for the shooting of these game species and the logical choice was to move up to the .375 H&H Magnum. ==Design & specifications==

The .375 H&H Magnum case design was conceived to use cordite; a stick type propellant used widely in the United Kingdom. The tapering cartridge body design and the small shallow shoulder are typical aspects of cartridges optimized for the use of this propellant. An advantage of such a case design is that it will feed and extract smoothly thus contributing to the cartridge's reliability in the field. Unlike previous cartridges, the .375 H&H operates at relatively higher pressures and was designed from the outset for use with smokeless powders that can generate higher pressures and thus higher velocities. However, when the cartridge was designed pressure levels were held to as cordite was sensitive to temperature and could cause dangerously high pressures in the hot tropical climates of Africa and India. However, modern smokeless powders are not as sensitive to ambient temperatures as cordite and therefore both the C.I.P. and SAAMI provide far higher allowable pressures than the original loading of the cartridge allowed. : C.I.P. recommends that commencement of rifling begin at . Bore diameter is given as and groove diameter is . C.I.P. recommends a six groove barrel contour with each groove having an arc length of and a twist rate of one rotation in . Maximum chamber pressure is given at . There are no discrepancies between SAAMI and C.I.P. values. However, C.I.P. measures angle α (shoulder angle) as 29°55'43". SAAMI measure the shoulder angle as α/2 which is given by SAAMI to be 15°. ==Performance==

When the .375 H&H Magnum was released in 1912 it was loaded with three bullet weights: a at , at and a at . However, today, with the availability of a wide range of powders, velocities gains of can be realized. Acceptable bullet weights for the .375 H&H Magnum range from to . The lighter bullets, those weighing to are suitable for lighter plains game. Bullets weighing between to can be used on heavy bodied plains game. Bullets weighing to should be reserved for heavy dangerous game. Today, a typical factory load such as Remington's R375M1 or Federal's ammunition will launch a spitzer bullet at with of energy at the muzzle. This load has approximately the same trajectory as the 180-grain (12 g) bullet from a .30-06 Springfield. However while the .30-06 generates only about compared with the .375 H&H. The spitzer bullet at .375 H&H velocities has a Maximum point-blank range (MPBR) of about when sighted in at about . The typical ammunition manufactured by Federal and Remington have a muzzle velocity of churning out of energy. The ammunition has a bullet trajectory similar to that of the .308 Winchester firing a bullet. The trajectory allows for a MPBR of about when zeroed in for . Hornady new Superformance line of cartridges provides a leap in performance to the .375 H&H cartridge. The Superformance line uses powders specifically blended for each cartridge. Hornady's 375 H&H 270 gr SP-RP Superformance ammunition fires a bullet at for while the 375 H&H 300 gr DGS Superformance fires a bullet at generating and of energy respectively. The 9.3×64mm Brenneke cartridge is the closest European continental ballistic twin of the .375 Holland & Holland Magnum. When compared to the .375 Holland & Holland Magnum the 9.3×64mm Brenneke uses a bullet of a slightly smaller diameter of versus the .375 H&H which uses a bullet a difference of only . ==Sporting usage==

The .375 H&H Magnum is one of the most versatile cartridges and is referred to by Jack O’Connor as the "Queen of the Medium Bores". The cartridge is very popular in Africa where it is considered one of the best all-round rifle cartridges. It is capable of taking any big species including all the Big Five game animals. The big game hunter, John "Pondoro" Taylor, held the .375 H&H Magnum in such high esteem that he dedicated a chapter to it in the book African Rifles and Cartridges. Ammunition loaded with the or heavier bullet on the .375 H&H is adequate for heavy thick-skinned dangerous game such as elephant and rhinoceros in most conditions. Today, due to the pace at which hunting is conducted and the requirement of success within certain time constraints, the .375 H&H Magnum is considered under powered for class 4 game like elephant, rhinoceros and buffalo as the only shooting situation that might present itself might be an adverse one. However, there is little doubt that it has been successfully used to take these heavy dangerous game species. There is some speculation that the .375 H&H Magnum has been used to take more Big Five game than any other cartridge. Even today, many professional hunters, outfitters and wildlife management personnel in Africa continue to rely on the .375 H&H Magnum to carry out their duties throughout the continent. Apart from hunting class 3 game, the .375 Holland & Holland Magnum is often used for last resort defense against dangerous class 3 game, particularly the great bears including grizzly, polar and brown bears. It is often carried by fishermen, hunters and guides in Alaska, Canada and European arctic regions like Greenland for protection as encounters with these larger bear species can be common. Bullets weighing will have sectional densities between .330 and .356. These bullets can be launched at velocities between giving these bullets greater penetration than a .458 bullet at . Bullets weighing are perfect for the largest cats such as the lion or tiger and other dangerous class 3 game. While these felines do not require extremely powerful cartridges, (a .300 Winchester Magnum can be considered a minimum for these cats), local requirements or regulations may require a larger cartridge than the .375 H&H Magnum. This range of bullets also is a great choice for most plains game species in Africa and for elk, red deer, and moose (called elk in Europe) in North America and Europe. There are a great number of rifles (and even a few handguns, such as adapted Howdah pistols) chambered for the .375 H&H. Many types of actions are used, including single-shot rifles, double-rifles, and bolt-action rifles. When hunting dangerous game, a double-rifle or a controlled-feed bolt-action rifle is most commonly recommended, as a quick follow-up shot may be necessary, and reliability of the firearm becomes of paramount importance. The one sport in which the .375 H&H Magnum has made some gains in has been the Big Bore Shoots such as those sponsored by the Big Bore Association of South Africa and its affiliated chapters. The .375 H&H Magnum is considered a transitional bore by the association and the minimum cartridge which is allowable for score keeping. ==Variants==

The .375 H&H Magnum's long tapering body and shallow shoulders are generally believed not to promote long case life due to case head separation above the belt. The case design does not promote the optimal use of the cartridge size to gain performance. Modern cartridges have very little taper so as to benefit from a larger powder capacity. There have been a few attempts to improve the performance of the cartridge. .375 Flanged Magnum The .375 Flanged Magnum (9.5×75mmR), also known as the .375 H&H Flanged Magnum is the companion cartridge to the .375 H&H Magnum for use in double rifles and was released together with the .375 H&H Magnum by Holland & Holland. It is a rimmed (flanged) cartridge and is loaded to a lower pressure level of . : The CIP has published mandatory specifications for the .375 Flanged Magnum. Bore ∅ for the cartridge is and the groove ∅ is . The barrel will have six grooves with a twist of one revolution in and each groove being wide. SAAMI has not published specifications nor recommendations in regard to this cartridge. The cartridge is capable of firing a bullet at , a bullet at and a bullet at with muzzle energies of , and respectively. The cartridge is appropriate for the same game species as the .375 H&H Magnum cartridge. .375 H&H Ackley Improved The .375 H&H Ackley Improved was a cartridge designed by P. O. Ackley in an effort improve on the performance and case life of the .375 H&H Magnum. The improved case follows the formulaic Ackley design of a body of little taper and steep shoulder of 40°. The cartridge was found to be capable of with a bullet. A .375 H&H Magnum cartridge can be chambered and fired safely in an Ackley Improved chamber but with a loss of performance, as some energy is lost fireforming the case to the chamber. A .375 H&H Magnum case thus fired will form to the Ackley Improved chamber. .375 Weatherby Magnum The .375 Weatherby Magnum is an improved case like the .375 H&H Ackley Improved. The case was designed by Roy Weatherby in 1944 and features the Weatherby double radius shoulder typical of all Weatherby cartridges. The .375 Weatherby Magnum is capable of launching a at . The .375 H&H Magnum can be fired in the chamber of a .375 Weatherby Magnum with a slight loss in performance. Unlike the .375 H&H AI cartridge, the .375 Weatherby Magnum is loaded to higher pressures than its parent cartridge. ==As a parent cartridge==

The distinctive belted case of this cartridge was patented in Britain on 31 March 1891 by G. Roth of Austria. The first commercial use of the patent was in 1907 for the .375 Holland-Schoenauer cartridge for a Mannlicher–Schoenauer bolt-action rifle marketed by Holland & Holland. The .375 H&H used an improved belted case shared with the .275 H&H Magnum when they were introduced together in August, 1912. This second belted case design was later used with the .300 H&H Magnum, and has been modified as the basis for "Magnum" cartridges developed by other arms manufacturers. Cartridges based on the full length .375 H&H Magnum case .244 H&H Magnum – based directly on the .375 H&H case 6.5-300 Weatherby Magnum – via the .300 Weatherby Magnum 7mm Shooting Times Westerner – via the 8mm Remington Magnum .30 Super – a modified variant of the .300 H&H Magnum produced by Winchester .300 H&H Magnum – based directly on the .375 H&H case .300 Weatherby Magnum – via the full length .30 Super improved 8mm Remington Magnum – necked down improved .375 H&H case .340 Weatherby Magnum – via the full length .30 Super improved .350 Griffin & Howe Magnum – based directly on the .375 H&H case .358 Shooting Times Alaskan – via the 8mm Remington Magnum .375 Weatherby Magnum – via the .30 Super improved .40 BSA Magnum .400 H&H Magnum – based directly on the .375 H&H case .416 Remington Magnum – via the 8mm Remington Magnum .458 Lott – via the .458 Winchester Magnum .470 Capstick – based directly on the .375 H&H case Standard length cartridges based on the .375 H&H Magnum case .257 Weatherby Magnum – via the .30 Super .26 BSA Magnum .264 Winchester Magnum – based directly on the .375 H&H case .270 Weatherby Magnum – via the .30 Super .275 H&H Magnum – developed along with the .375 in 1912 7×61mm S&H – via the .275 H&H Magnum 7mm Remington Magnum – based on the .375 H&H case via the .264 Winchester Magnum case 7mm Weatherby Magnum – via the .30 Super .300 Winchester Magnum – based directly on the .375 H&H case .308 Norma Magnum – used standard length Weatherby cases .33 BSA Magnum .338 Winchester Magnum – based directly on the .375 H&H case .358 Norma Magnum – used standard length Weatherby cases .458 Winchester Magnum – based directly on the .375 H&H case Short action cartridges based on the .375 H&H Magnum case 6.5mm Remington Magnum – via the .350 Remington Magnum .350 Remington Magnum – via the 7mm Remington Magnum .450 Marlin – via the .458 Winchester Magnum ==See also==