The .375 Holland & Holland Magnum, often abbreviated to .375 H&H Magnum, is a medium-bore rifle cartridge introduced in 1912 by London based gunmaker Holland & Holland. The .375 H&H cartridge featured a belt to ensure the correct headspace, which otherwise might be unreliable, given the narrow shoulder of the cartridge case. The cartridge was designed to use cordite which was made in long strands – hence the tapered shape of the case, which, as a beneficial side effect also helped in smooth chambering and extraction from a rifle's breech.
The .375 H&H often is cited as one of the most useful all-round rifle cartridges, especially in shooting large and dangerous game. With bullet weights ranging from 235 grains (17 g) to 350 grains (23 g), it has the necessary punch for small to medium game, as well as large, thick-skinned dangerous game. The most common bullet weight available in this caliber is 300 grains (19 g). In many regions with thick-skinned dangerous game animals, the .375 H&H is seen as the minimum acceptable caliber, and in many places (primarily in Africa) it is now the legal minimum for hunting such game. African game guides, professional hunters, and dangerous game cullers have repeatedly voted the .375 H&H as their clear preference for an all-round caliber if they could have only one rifle. Alaskan game guides have expressed a similar preference for brown bear and polar bear country.
Unlike many other chamberings, .375 H&H Magnum rifles achieve nearly the same point of impact over a wide range of bullet weights at all commonly used distances. This simplifies a hunter's choice in selecting different bullet weights, based upon the game hunted, by requiring fewer scope or sight adjustments, which further serves to popularize the .375 H&H Magnum among professional hunters.
History and origins 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 and was soon adopted by Westley Richards and Eley as the .375 Rimless Nitro Express 2.25". In an effort to compete, Holland & Holland introduced the .400/375 Belted Nitro Express.
.400/375 Belted Nitro Express was developed in 1905 and the 9.5×57mm MS – just in 1908.
The .400/375 H&H (also known as the .375 Velopex) as it is sometimes known was the first cartridge manufactured to feature a belt. The addition of a belt to a rimless cartridge design provided the advantage of allowing for correct headspacing of highly tapered cartridges (an advantage of flanged cartridges) and smooth feeding through magazine rifles (the advantage of rimless cartridges).
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.
This trend did not go unnoticed by British rifle manufacturers. Between 1909 and 1911 Holland & Holland, Jeffery, Rigby, and Westley Richards introduced their own cartridges: .375 H&H Magnum, .404 Jeffery, .416 Rigby, and the .425 Westley Richards in an effort to stem the tide of the 9.3×62mm.
Holland & Holland decided that the rifle had to fire a bullet with an adequate sectional density as the bullet of the 9.3×62mm Mauser cartridge which had demonstrated that it had the required penetration on thick skinned dangerous game. Secondly, the cartridge would require a high velocity so as to provide this penetration at extended ranges. Thirdly, the cartridge must function reliably through a magazine rifle in tropical conditions and this required a tapered case working at lower pressures. Holland & Holland had determined that to provide adequate penetration a bullet with the sectional density similar to the 9.3×62mm required impact velocities of about . Drawing from anecdotal evidence of hunters it was also determined that high velocities provided impressive kills on game. Another added advantage of the high velocities was that a range misjudgment would be mitigated by the flatter trajectory of a HV projectile.
Holland & Holland's new cartridge was named .375 Holland and Holland Magnum, and was released together with a flanged or rimmed version (.375 Flanged Magnum also known as the .375 Nitro Express). It featured the belt from the .400/375 H&H cartridge, fired a bullet which had the same sectional density of the 9.3×62mm bullet at a velocity of . The cartridge burned cordite and had a rather low working pressure of by modern standards so that spent cases would extract reliably in the tropical environments of India and Africa.
Original cordite loads were as follows:
62 grains for the 235-gr bullet, yielding a listed 2,800 feet per second 61 grains for the 270-gr bullet, yielding a listed 2,650 feet per second 58 grains for the 300-gr bullet, yielding a listed 2,500 feet per secondKen Waters, Pet Loads, p. 440
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 a versatile cartridge and is referred to by Jack O’Connor as the "Queen of the Medium Bores". The cartridge is very popular in Africa; in part because it is capable of killing large species including all 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.