.375 H&H Magnum

.375 H&H Magnum
.375 H&H Magnum (Left) with .338 Winchester Magnum (Right) and US Quarter for scale
Type	Rifle
Place of origin	United Kingdom
Production history
Designer	Holland & Holland
Designed	1912
Produced	1912–present
Variants	.375 H&H Ackley Improved, .375 Weatherby Magnum
Specifications
Parent case	Unique
Bullet diameter	.375 in (9.5 mm)
Neck diameter	.404 in (10.3 mm)
Shoulder diameter	.448 in (11.4 mm)
Base diameter	.513 in (13.0 mm)
Rim diameter	.532 in (13.5 mm)
Rim thickness	.050 in (1.3 mm)
Case length	2.850 in (72.4 mm)
Overall length	3.6 in (91 mm)
Case capacity	95.3 gr H2O (6.18 cm3)
Rifling twist	1-12" (304.8 mm)
Primer type	large rifle magnum
Maximum pressure	62,000 psi (430 MPa)
Ballistic performance
Bullet weight/type Velocity Energy 200 gr (13 g) JFP 3,195 ft/s (974 m/s) 4,534 ft·lbf (6,147 J) 235 gr (15 g) SP 2,964 ft/s (903 m/s) 4,585 ft·lbf (6,216 J) 250 gr (16 g) SP 2,835 ft/s (864 m/s) 4,463 ft·lbf (6,051 J) 270 gr (17 g) FS 2,694 ft/s (821 m/s) 4,352 ft·lbf (5,901 J) 300 gr (19 g) SPBT 2,645 ft/s (806 m/s) 4,661 ft·lbf (6,319 J)
Source(s): Hodgdon Online Reloading Data

The .375 Holland & Holland Magnum (9.5×72mmB) is a medium-bore rifle cartridge. The .375 H&H was only the second cartridge ever to feature a belt, now common among magnum rounds.^[1] On these new rimless cartridges the belt replaced the rim in ensuring the correct headspace, which otherwise might be unreliable, given the narrow shoulder of the cartridge case.^[2] The British company Holland & Holland introduced the cartridge in 1912 as the .375 Belted Rimless Nitro-Express. It initially used cordite propellant which was made in long strands – hence the tapered shape of this cartridge, which also ensured smooth chambering and extraction from a rifle's breech.^[3]

The .375 H&H often is cited as one of the most useful all-round rifle cartridges, especially in shooting large and dangerous game.^[4] With relatively light bullets in the region of 235 to 270 grains (15 to 17 g), it is a flat-shooting, fairly long-range cartridge ideal for use on light to medium game, whereas with heavy bullets of 300 grains (19 g) and greater, it has the punch necessary for large, thick-skinned dangerous game. In many regions with thick-skinned dangerous game animals, the .375 H&H is seen as the minimum acceptable caliber, and in many places (in Africa, primarily) it is now the legal minimum for hunting such game. African game guides, professional hunters, and cullers of dangerous game have repeatedly voted the .375 H&H as their clear preference for an all-round caliber if they could only have one rifle. A similar preference has been expressed by Alaskan game guides for brown bear and polar bear country^[3]

Unlike what is seen in most calibers, many .375 H&H rifles also achieve nearly the same point of impact over a wide range of bullet weights at all commonly used distances, further simplifying a professional hunter's choice in selecting different grain bullets based upon the game hunted. This requires less scope or sight adjustments, which further serves to popularize the .375 H&H Magnum among professional hunters.^[5][6]

History & origins

.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^[1] 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. 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).^[7]

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 cheaper 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.^[8] 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 Elephant to the dik-dik and had acquired a reputation to match.^[7]

This trend did not go unnoticed by British rifle manufacturers. Between 1909 and 1911 Holland & Holland, Jeffrey, Rigby and Westley Richards introduced their own competing designs: .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. Furthermore, the influence of the high-velocity craze begun by the Canadian .280 Ross rifle had a marked effect on the Holland & Holland’s final design which also drew from their experience with the .400/.375 H&H cartridge.^[7]

Holland & Holland decided that the rifle had to fire a bullet with an adequate sectional density as the 286 gr (18.5 g) 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. The high velocity of the cartridge would have the added advantage of serving as a marketing tool. 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 2,150 ft/s (660 m/s). 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.^[7]

Holland & Holland’s new cartridge was released together with a flanged or rimmed version (.375 Flanged Magnum also known as the .375 Nitro Express) and was named the .375 Belted Rimless Nitro Express. It featured the belt from the .400/375 H&H cartridge, fired a 300 gr (19 g) bullet which had the same sectional density of the 286 gr (18.5 g) 9.3×62mm bullet at a velocity of 2,500 ft/s (760 m/s). The cartridge burnt cordite and had a rather low working pressure of 47,000 psi (3,200 bar) by modern standards so that spent cases would extract reliably in tropical environments of India and Africa.^[7]

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 the 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.^[7]

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 cartridge available and which could be easily put to use hunting dangerous game in North America. Winchester was the first US gun maker to produce rifles chambered for the cartridge and did so beginning in 1925.^[7]

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 enacting legislation stipulating that the 9.3 mm (0.37 in) or the .375 in (9.5 mm) 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.^[7]

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.^[9] 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 47,000 psi (3,200 bar) 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 CIP and SAAMI provide far higher allowable pressures than the original loading of the cartridge allowed.

CIP recommends that commencement of rifling begin at 8.91 mm (0.351 in). Bore diameter is given as 9.30 mm (0.366 in) and groove diameter is 9.55 mm (0.376 in). CIP recommends a six groove barrel contour with each groove having an arc length of 2.92 mm (0.115 in) and a twist rate of one rotation in 305 mm (12.0 in). Maximum chamber pressure is given at 4,300 bar (62,000 psi). There are no discrepancies between SAAMI and CIP values. However, CIP 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 235 gr (15.2 g) at 2,800 ft/s (850 m/s), 270 gr (17 g) at 2,650 ft/s (810 m/s)and a 300 gr (19 g) at 2,500 ft/s (760 m/s).^[10] However, today, with the availability of a wide range of powders, velocities gains of 150–200 ft/s (46–61 m/s) can be realized. Acceptable bullet weights for the .375 H&H Magnum range from 200 gr (13 g) to 380 gr (25 g). The lighter bullets, those weighting 210 gr (14 g) to 235 gr (15.2 g) are suitable for lighter plains game. Bullets weighting between 250 gr (16 g) to 285 gr (18.5 g) can be used on heavy bodied plains game. Bullets weighting 285 gr (18.5 g) to 300 gr (19 g) should be reserved for heavy dangerous game.

Today, a typical factory load such as Remington’s R375M1 or Federal’s ammunition will launch a 270 gr (17 g) spitzer bullet at 2,690 feet per second (820 m/s) with 4,337 ft·lbf (5,880 J) 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 2,914 ft·lbf (3,951 J) compared with the .375 H&H. The 270 gr (17 g) spitzer bullet at .375 H&H velocities has a maximum point blank range (MPBR) of about 260 yd (240 m) when sighted in at about 220 yd (200 m).

The typical 300 gr (19 g) ammunition manufactured by Federal and Remington have a muzzle velocity of 2,530 feet per second (770 m/s) churning out 4,263 ft·lbf (5,780 J) of energy. The 300 gr (19 g) ammunition has a bullet trajectory similar to that of the .308 Winchester firing a 180 gr (12 g) bullet. The trajectory allows for a MPBR of about 245 yd (224 m) when zeroed in for 210 yd (190 m).

Scant attention is paid today to bullets in the 225–235 gr (14.6–15.2 g) weight range. At present the 235 grain loadings are only available from Holland & Holland or Kynamco. Bullets in this weight range can be launched at velocities of 2,800–2,900 ft/s (850–880 m/s).

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 270 gr (17 g) bullet at 2,800 ft/s (850 m/s) for while the 375 H&H 300 gr DGS Superformance fires a 300 gr (19 g) bullet at 2,670 ft/s (810 m/s) generating 4,699 ft·lbf (6,371 J) and 4,748 ft·lbf (6,437 J) of energy respectively.

The 9.3×64mm Brenneke cartridge is probably 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 .366 in (9.3 mm) versus the .375 H&H which uses a .375 in (9.5 mm) bullet a difference of only .009 in (0.23 mm).

Sporting usage

Game Class vs 6 inch Maximum Point Blank Range of some 375 Magnum cartridges

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".^[11] 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.^[12] The big game hunter, John "Pondoro" Taylor, held the .375 H&H Magnum in such high esteem that he dedicated a chapter in the book African Rifles and Cartridges.

Ammunition loaded with the 300 gr (19 g) or heavier bullet the .375 H&H is adequate for heavy thick skinned dangerous game such as elephant and rhinoceros in most conditions. Today, due to 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.

Bullets weighing 325–350 gr (21.1–22.7 g) will have sectional densities between .330 and .356. These bullets can be launched at velocities between 2,380–2,470 ft/s (730–750 m/s) giving these bullets greater penetration than a 500 gr (32 g) .458 bullet at 2,240 ft/s (680 m/s).

Sectional Density vs Ballistic Coefficient of some 375 Magnum cartridges

Bullets weighing 250–270 gr (16–17 g) 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, 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-shots, double-rifles, and bolt actions. 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.^[13]

Variants

The .375 H&H Magnum 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. It comes as no surprise that 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 or .375 Flanged Nitro Express, is the companion cartridge to the .375 H&H Magnum for use in double and single shot rifles and was released together with the .375 H&H Magnum by Holland & Holland. It is considered the flanged (rimmed) version of the .375 H&H Magnum. The flanged cartridge is loaded to a lower pressure of 3,250 bar (47,100 psi) in comparison to the .375H&H Magnum.

The CIP has published mandatory specifications for the .375 Flanged Magnum. Bore ∅ for the cartridge is 9.30 mm (0.366 in) and the groove ∅ is 9.55 mm (0.376 in). The barrel will have 6 grooves with a twist of one revolution in 305 mm (12.0 in) and each groove being 2.92 mm (0.115 in)wide. SAAMI has not published specifications nor recommendations in regard to this cartridge.

The cartridge is capable of firing a 235 gr (15.2 g) bullet at 2,800 ft/s (850 m/s), a 270 gr (17 g) bullet at 2,650 ft/s (810 m/s) and a 300 gr (19 g) bullet at 2,500 ft/s (760 m/s) with muzzle energies of 4,090 ft·lbf (5,550 J),4,200 ft·lbf (5,700 J) and 4,160 ft·lbf (5,640 J) respectively. The cartridge is appropriate for all 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 2,830 ft/s (860 m/s) with a 270 gr (17 g) bullet. A .375 H&H Magnum cartridge can be chambered and fired safely in an Ackley Improved chamber but with a loss of performance. A .375 H&H Magnum case thus fired will form to the Ackley Improved chamber.

.375 Weatherby Magnum

The .375 Weatherby Magnum is in reality 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 300 gr (19 g) at 2,800 ft/s (850 m/s). 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 the 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.^[14] 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
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 – based directly on the .375 H&H case
.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

• List of rifle cartridges
• Table of handgun and rifle cartridges
• 9 mm caliber

Footnotes

External links

Wikimedia Commons has media related to .375 H&H Magnum.

• The .375 H&H Magnum Website
• Improving the .375 H&H Magnum
• The Reload Bench – .375 H&H Mag
• .375 H&H Magnum A Hunting Classic