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.300 Holland & Holland Magnum


Designed by the British firm Holland & Holland, the .300 H&H magnum was introduced in 1925, based on the .375 H&H magnum case necked down to .30 caliber.
By 1888 the famous Mauser company of Germany had designed a rimless cartridge which gave reliable feeding in bolt action magazine fed rifles, influencing cartridge design worldwide and forever more. When H&H set about designing their own cartridges for use in bolt action rifles, it was realized that a rimless case head would not on its own prove reliable based on H&H’s existing cartridge designs. H&H cartridges traditionally featured a large degree of body taper and gently sloping shoulders in order to aid extraction of cases during worst case scenarios. Head spacing and extraction at this time was obtained via a flanged rim. When attempting to match a rimless case head design to the H&H case, H&H realized that a shallow shoulder would not give positive head spacing, detrimental to both accuracy and extraction. To counter this a small belt was added at the case head, allowing H&H to utilize their tapered case design.
The belted case was first introduced by Holland & Holland on the .400 and .375 NE cartridges in 1904 followed by the famous .375 H&H magnum in 1912 with the .300 H&H arriving 13 years later.
Bolt action Holland & Holland rifles were typically based on extensively reworked model 98 Mauser actions.  With hundreds of man hours spent engraving and finishing rifles, only the most affluent of hunters could afford an H&H rifle. The .300 H&H was a proprietary cartridge patented by Holland and Holland, meaning that no other manufacturer could build rifles or ammunition for the .300 without the firm’s consent. For these reasons, the .300 H&H initially received little attention outside of Britain’s upper class. Ammunition at this time was loaded by Kynoch with bullet weights and velocities duplicating .30-06 Springfield factory ammunition.
When New York custom gun firm Griffin & Howe were formed in 1923 with an interest in building fine sporting rifles, chamberings were based on company member Col. Townsend Whelen’s .30-06 wildcat designs. During the later 1920’s, Holland & Holland released the patent rights to the .375 and .300 cartridges, allowing Griffin & Howe, along with other manufacturers, to build rifles and ammunition in these calibers. Still, for nearly a decade the .300 H&H went mostly unnoticed by the general shooting public. But in 1935, American shooter Ben Comfort used a Griffin & Howe .300 H&H Magnum built on an M1917 action to win the 1000 yard Wimbledon cup. 
Following the Wimbledon Cup victory the .300 H&H Magnum cartridge obtained widespread attention in the U.S.A, influencing future cartridge designs. The belt of the H&H case and the term ‘Magnum’ were viewed as features that went hand in hand. To be of magnum power, it was considered that a cartridge must have a ‘reinforcing’ belt. Therefore, although later cartridge designs featured appropriate shoulder angles for reliable head spacing without the need of a belt, the belted case was an easy marketing ploy to symbolize magnum power.
In 1937, Winchester offered the Model 70 bolt action in both .300 and .375 H&H Magnum chamberings. This was the first major manufacturer to offer these cartridges to the general public at affordable prices. In support of this, the Western cartridge company offered a variety of loadings for the .300 H&H which eventually, thanks to advances in powder design, were some 200fps faster than original loadings.  
The .300 H&H was in its heyday, enjoyed both as an African plains game cartridge, a North American game cartridge and an effective competition chambering. As a plains game cartridge, the .300 was very well suited to a huge variety of game. That said, human curiosity would of course see the .300 used on large heavy animals, at times much beyond the capacity of the bore diameter, bullet weights and bullet construction of the day. The basic and sometimes very explosive cup and core projectile designs employed during these formative years had great strengths, but not without limitations.
Eventually, the .300H&H was superseded by newer .30 caliber magnum cartridges including the .300 Weatherby Magnum introduced in 1944, followed by the .308 Norma and .300 Winchester Magnums introduced during the 1960’s. More recently, the addition of non-belted magnums has flooded the market with .30 caliber magnum powered cartridge designs. Nevertheless, the .300 Holland & Holland continues to see use. Original rifles are highly prized as collector’s items while the occasional enthusiast will build a custom rifle chambered in .300 H&H for reasons of both nostalgia and performance.


The .300 H&H is a potent cartridge, thoroughly suited to medium game hunting but with the flexibility to produce fast killing on both light game as well as large animals.
Loaded with 150 grain bullets to velocities of around 3250fps, the H&H is capable of producing fast and often spectacular kills on light or lean game.
Loaded with appropriately constructed 165 grain projectiles at around 3100fps, the .300 H&H can be used to great effect on a wide range of game body weights.
Utilizing 180 grain bullets at up to 3000fps, the .300 H&H is highly effective on larger medium game, rendering deep, broad wounding.
When loaded with premium 200-220 grain bullets at 2600-2800fps, the H&H can also be asked to reliably tackle heavy game, however, as is reiterated throughout these texts, the .30 calibers cannot be expected to render wide wounding on large heavy game with ordinary chest shots. Premium bullets combined with head and or neck shots produce the most reliable results on Bovine sized animals.
As a long range hunting cartridge, the .300 H&H has the potential, when loaded with highly frangible projectiles to render wide wounding out to ranges of at least 1000 yards, remaining supersonic out to ranges of around 1400 yards. Readers may be interested to know that there are a few retro enthusiasts currently using the .300 H&H at these ranges.

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Factory Ammunition

Federal and Hornady are the last of the major manufacturers to offer .300 H&H factory ammunition.  The Federal load features the excellent 180 grain Nosler Partition at a true 2880fps. This is a fast expanding bullet, ideally suited to game weighing between 90 and 320kg (200-700lb), producing wide wounding at lower velocities of 1600-1800fps. The Partition is somewhat flexible on lighter game, rendering wide wounds but sometimes slightly delayed killing and can also be pushed to tackle game heavier than 700lb, but is not ideal for truly heavy game.  The Hornady load, featuring the 180 grain InterBond is much stouter than the Partition and on lean game, can produce very delayed kills, especially at impact velocities below 2600fps. Like the Federal load, the InterBond is best suited to game weighing between 90-320kg but is best used at ranges where impact velocities remain above 2200fps.

Hand Loading

The .300 H&H magnum can be hand loaded to produce velocities of 3250fps with 150 grain bullets, 3000fps with 180 grain bullets, 2800fps with 200 grain bullets and 2600fps with 220 grain bullets. That said, those who own collectable rifles may wish to utilize softer, lower wear hand loads of around 100fps slower than the velocities listed above.

The case length of the .300 H&H is 2.850”, longer than the 7mm Remington Magnum or .300 Winchester Magnum, duplicating the case length of the .300 Weatherby and Remington Ultra Magnums. Traditionally, firms like Holland & Holland had to go to great extremes lengthening the magazines of Mauser rifles to house such a long cartridge. Occasionally, a shooter may come across an old private custom build, based on a rifle action (magazine box length) that was not ideally suited or modified to suit the H&H, suffering limited COAL’s. When hand loading or creating a retro custom build, these factors need to be taken into consideration.
H&H cases can be sized in such a way as to head space against the belt and the gentle shoulder at the same time and through attention to reloading technique along with the very long case neck, the resulting optimum concentricity has the potential for excellent accuracy. The most suitable powders for all bullet weights in the .300 H&H are those in the 4831 range. Performance of hand loads in the H&H  is very similar to the shorter but blown out .300 Winchester Magnum, with top velocities only 50 to 100 fps below the Win mag. To this end, bullet performance can be sought from the .300 Winchester magnum text. 

Closing Comments

The .300 H&H Magnum spawned the design of our modern belted magnum cartridges, an integral part of  the story of cartridge development over the last 100 years. Though it is now a very rare chambering, the .300 still retains a small degree of popularity, as do the highly prized H&H and Griffin & Howe rifles. History aside, the .300 H&H is a very versatile and highly effective medium game cartridge. 
Suggested loads: .300 H&H Barrel length: 26”
No ID   Sectional Density Ballistic Coefficient Observed  MV Fps ME
1 FL Federal 180gr Partition .271 .474 2880 3315
2 HL 150gr Partition/Interlock .226 .387 3250 3517
3 HL  178gr A-Max .268 .495 3000 3497
4 HL 200gr Woodleigh PP Mag .301 .450 2800 3481
Suggested sight settings and bullet paths           
1 Yards 100 150 260 300 325 350 375 400
  Bt. path +3 +3.5 0 -3 .5.5 -8.3 -11.6 -15.3
2 Yards 100 175 297 337 350 375 400  
  Bt. path +3 +3.9 0 -3 -4.2 -6.7 -9.6  
3 Yards 100 150 278 318 350 375 400  
  Bt. path +3 +3.7 0 -3 -6 -8.7 -11.9  
4 Yards 100 150 249 287 300 325 350  
  Bt. path +3 +3.4 0 -3 -4.2 -6.9 -10.1  
No At yards 10mphXwind Velocity Ft-lb’s
1 300 6.3 2319 2148
2 300 6.7 2517 2109
3 300 5.3 2480 2389
4 300 7.1 2213 2175
 300 H&H 001.jpg
.300 H&HH&H Imperial Metric 
A .532 13.5
B .513 13.03
C 8 deg  
D .450 11.43
E .338 8.58
F 2.105 53.46
G .371 9.42
H 2.850 72.39
Max Case 2.850 72.4
Trim length 2.840 72.1
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