May 28, 2022
The .300 H&H Mag. was introduced in 1925 by the British firm Holland & Holland. It was the first of many offspring to be spawned by the earlier .375 H&H Mag. Both were given belted cases for positive headspacing. Choosing a bullet diameter of 0.308 inch will always remain a mystery because it is an odd duck among cartridges designed by the British.
The .303 Mag. introduced in 1919 had a nominal 0.312-inch bullet, and its case was similar in size to the .30-06 Springfield. The .303 Mag. and the .303 British military cartridge adopted in 1888 shared the exact same bullet diameter so for tradition’s sake, the new belted cartridge should have been called the .303 H&H Mag.
Whatever the reason might have been, it was a good one because giving the cartridge the same bullet diameter as the .30-06 Springfield ensured its acceptance among American hunters. That bullet diameter also made it easy for Winchester and Remington to begin loading .300 H&H Mag. ammunition and for Winchester to chamber the Model 70 rifle for it in 1937.
At the time of the .375’s introduction, Holland & Holland was building rifles on modified actions from the Mauser factory in Oberndorf, Germany. While experimenting with cartridge cases of various shapes, it was concluded that considerable body taper combined with a mild, 15-degree shoulder angle resulted in smooth feeding of cartridges from magazine to chamber. This was considered most important in a rifle/cartridge combination designed for use on potentially dangerous game.
While the .300 H&H Mag. case has the same body taper as the .375 case, its shoulder angle is a milder 8 degrees, 30 minutes. The result was perhaps the smoothest feeding big game cartridge ever designed.
The two H&H cartridges were immediate hits among those who could afford to buy an English-built magazine rifle, but they were beyond the budgets of most hunters. Griffin & Howe offered custom rifles on the Remington Model 30 action chambered for both cartridges, but they also were quite expensive.
The Griffin & Howe target rifle used by Ben Comfort to win the prestigious 1,000-yard Wimbledon Cup match at Camp Perry in 1935 was on that action, and it had a heavy barrel built by Winchester in .300 H&H Mag. Popularity of the cartridge among long-distance target shooters actually began during the late 1920s, and by the time Comfort got around to giving it a try, Remington and Western Cartridge Company were offering match-grade ammunition loaded with 180-grain full-metal-jacket bullets of boattail form. He won the match with Western ammo.
Comfort’s win at Camp Perry made many Americans aware of the .300 H&H Mag., but its lack of availability in a more affordable rifle kept it from becoming equally successful as a big game cartridge. Then came 1937 and the introduction of the Winchester Model 70 in that caliber. The standard-grade rifle sold for $61, and when the price of a Noske or Zeiss scope was added, it cost less than a third as much as most imported rifles in .300 H&H Mag.
The cartridge was originally loaded with cordite, which was formed of strands resembling dried spaghetti that were long enough to reach from the base of the cartridge case to the beginning of its shoulder. Linen string was often used to tie a number of strands into a bundle prior to it being placed inside the case, and since this made insertion into a necked-down case impossible, the bundle was inserted prior to that operation.
Cordite had an extremely high nitroglycerin content, which made it quite erosive on barrels. Even worse, pressures fluctuated widely when it was subjected to extremes in ambient temperature.
Realizing the .300 H&H would be exposed to the tropical climates of Africa and India, the British loaded it to about the same chamber pressure as the .30-30 Win., and that reined back its performance to about the same as for American loadings of the .30-06 Springfield. Velocity ratings for bullets weighing 150, 180 and 200 grains were 3,000, 2,700 and 2,350 fps respectively.
The use of less temperature-sensitive propellants allowed Western and Remington to increase chamber pressures. Velocities leaped to 3,060 fps for a 180-grain bullet and 2,730 fps for a bullet weighing 220 grains. Those were from a 24-inch barrel, and actual velocity of the 180-grain load often exceeded 3,100 fps from a 26-inch barrel. At the time, .30-06 factory ammo loaded with a bullet of the same weight was rated at 2,690 fps.
In addition to the Model 70 with a standard-weight 26-inch barrel in .300 H&H Mag., Winchester cataloged several target versions, all considerably less expensive than the Griffin & Howe rifle used by Ben Comfort. Weights were 9.5 pounds for the National Match rifle with a standard-weight barrel, 10.5 pounds for the Target Model rifle with a bit heavier barrel and 13.25 pounds for the Bull Gun.
Other rifles that spring to mind were the Colt Coltsman, Browning High Power and the Sako Hi-Power, all on the FN Mauser action. At a price of $107, the Remington Model 721 was the least expensive route to a rifle in .300 H&H Mag. during the 1950s.
Remington did a limited run of Model 700 Classics in 1983, and a few Ruger No. 1s have been chambered for the old cartridge. I have seen a Browning X-Bolt in that caliber, but not many were built.
The decline in popularity of the .300 H&H Mag. began during the 1950s with the availability of cheap military-surplus 1903 Springfield and 1898 Mauser rifles. Gunsmiths across the country were busy building thousands of rifles on those actions, and both were too short for the British cartridge. This led to the development of shorter wildcats on the H&H case by P.O. Ackley and others.
The first factory-loaded threat arrived from Sweden in 1960. While visiting the Norma factory about 10 years ago, I discussed the .308 Norma Mag. with a long-time company employee who was familiar with its development for the American market. According to him, company design specifications called for a cartridge capable of delivering .300 H&H Mag. velocities, yet be short enough to squeeze into the magazines of ’03 Springfield and ’98 Mauser actions.
The primary goal was accomplished. I still have a few .308 Norma cases as well as a box of Winchester .300 H&H cases, both made during the 1950s. When filled to the brim with water, the .300 H&H case holds a half-grain more. Unprimed cases became available, but due to the delayed arrival of loaded ammunition, the .308 Norma Mag. never really had a chance.
While the introduction of the .300 Win. Mag. in 1963 was bad news for the old British cartridge, the difference in their potential performance is not enough to matter. In a comparison of Hornady cases, water capacity of the .300 H&H Mag. is only one grain less than for the .300 Win. Mag. case. For cases of that size, such a minor difference in capacity has an insignificant bearing on chamber pressure and velocity.
Everything—including barrel length and the pressure to which the two cartridges are loaded—being equal, their velocity is the same. But all is not equal, and why the Winchester cartridge is loaded to higher chamber pressure remains a mystery.
Considering that the .300 H&H Mag. has generally been available only in rifles with extremely strong actions, loading it to lower pressure makes no sense. Data in some of the old reloading manuals pushed 180-grain bullets to 3,100 fps, and while some of today’s manuals approach that velocity, others fall far short. Data published by Hodgdon, Western and Lyman show close to the same maximum speeds for the two cartridges. Perhaps the time has come for a +P factory loading.
Hornady, Nosler and Federal load the ammunition. It is also cataloged by Kynoch with a 180-grain bullet at the original velocity of 2,700 fps. Unprimed cases available from Nosler and Hornady make the grand old British cartridge an excellent candidate for handloading.