375 HH Magnum
.375 H&H Magnum
Country of origin

United Kingdom


Holland & Holland

Year(s) designed


Year production began


Year production ended


Cartridge type


Parent cartridge


Overall length

3.60in (91.0mm)

Case length

2.850in (72.4mm)

Neck diameter

0.404in (10.3mm)

Shoulder diameter

0.448in (11.4mm)

Base diameter

0.513in (13.0mm)

Rim diameter

0.532in (13.5mm)

Rim thickness

0.050in (1.3mm)

Rifling twist

1:12in (304.8mm)

Muzzle velocity

2,645ft/s (806m/s) - 3,195ft/s (974m/s)

Primer type

Large rifle


The Queen of the Medium Bores

–Jack O'Connor, Dean of American Gun Writers,[1]

The .375 Holland & Holland Magnum (9.5x72mmB) is a cartridge, designed by British based manufacturer Holland & Holland in 1912.[2] The .375 H&H was one of the earliest cartridges to feature a belt to maximise head space, and has formed the parent case for numerous other cartridges including the .375 Weatherby Magnum and .450 Marlin.[2]


With the increasing influence of German cartridges on hunting rifles, British manufacturers began to develop larger calibre cartridges to hunt big game.[2] Holland & Holland were among the first to release a competing cartridge to the Mauser developed 9.3x62mm that had become one of the most widespread and easy to obtain cartridges in the hunting world.[2] The .375 H&H Magnum was the result of their endeavours.

The .375 H&H was also novel in that it used cordite, and hence produced a relatively low (by modern standards) pressure of 47,000psi, which meant that the cartridge could be exctracted with relative ease (ie it would not deform as much as a higher pressure round).[2] Later developments of the cartridge replaced the cordite with more modern powder mixes, with the maximum pressure also increasing.[1]

The First World War and its aftermath prompted Holland & Holland to produce the .375 H&H on a more general basis for the first time, openly selling the cartridge to the general public in 1919.[2] The Second World War, however, was the key to the .375 H&H's continued success, as major manufacturers such as Winchester began focusing on the civilian market.[2] The cartridge of choice for the new wave of hunting rifles: The .375 H&H Magnum.

Design DetailsEdit

The .375 H&H Magnum was designed from the ground up, with Holland & Holland designing a brand new, belted, case for their new creation.[1] The overall design of the case was influenced by the choice of cordite as a propellent, which required a tapered casing with shallow shoulder for optimum performance.[2] This aided the extraction of the .375 H&H as it operated more smoothly with the mechanism of the rifle it was used in, a fact that helped to establish its reputation and popularity as a hunting cartridge.[2]


The figures below are based on the performance statistics of .375 H&H Magnum cartridges produced and sold by Hornady.

Name Muzzle Velocity (ft/s) Energy (ft-lbs)
250gr 375 GMX® Superformance 2,890 4,636
270gr Interlock® SP-RP 2,700 4,370
300gr DGX® 2,630 4,263
All figures from the Hornady website.[3]

These figures demonstrate that the .375 H&H is more powerful than its major rival, the 9.3x62mm Mauser, although the German cartridge is cheaper to obtain.[2] That said, popularity of the .375 H&H has been established by both its performance and reliability through use.[1]


The .375 H&H was produced with a couple of variations of its design, both of which had unique features to change the potential potentcy of the original design.

.375 "Flanged" MagnumEdit

The competition version of the .375 H&H Magnum, and originally released alongside the original design.[2] Often used with a 300 grain bullet, the .375 Flanged fires at a lower pressure, but will also take down the largest of game animals as effectively as larger calibres.[1]

.375 H&H Ackley "Improved"Edit

A version of the .375 H&H produced by P.O. Ackley, who hoped to improve the power of the standard cartridge.[2] Features a steeper, 40 degree shoulder slope, and is capable of firing a 270gr bullet at 2,830ft/s, a small improvement.[2] Although this cartridge may be used in chambers fitted for the standard round, there is a significant reduction in power as a result, meaning that a Ackley Improved chamber must be used for optimal performance.[2]

.375 Weatherby MagnumEdit

Designed by Roy Weatherby in 1944, the .375 Weatherby Magnum essentially features minor modifications to the case design, and was the first cartridge to use the .375 H&H as a parent.[2] The Weatherby is capable of firing at higher pressures, and can achieve muzzle velocities of 2,800ft/s with a 300 gr bullet.[2]


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