The .300 Holland & Holland Magnum
By Chuck Hawks
The first belted magnum rifle case was the .375 invented by the renowned London firm of Holland and Holland before the First World War. In 1920 H&H brought out their .300 Magnum cartridge, based on the same case necked down to accept .308 inch bullets, which is called the .300 Belted Rimless Magnum or H&H Super .30 in Britian. Its case has been the basis for most of the magnum cartridges designed ever since. The traditional British factory load drove a 180 grain bullet at a muzzle velocity (MV) of 2750 fps with muzzle energy (ME) of 3020 ft. lbs.
There is also a rimmed version designed for use in double barreled rifles called the .30 Flanged Magnum. This is factory loaded to lower pressure than the rimless version of the case, resulting in a MV of only 2575 fps and ME of 2653 ft. lbs. with a 180 grain bullet. Today this cartridge is pretty well obsolete, as double rifles have been adapted to the .300 Belted Rimless Magnum.
The .300 H&H Mag. case has a lot of body taper and a very sloping 8.5 degree shoulder, intended to work with British long strand cordite powder. This design resulted in a cartridge that feeds very reliably from the box magazines typical of repeating rifles, which helped to make it popular in Africa for use on thin-skinned dangerous game.
The .300 H&H has a very long case, measuring 2.85 inches, and an overall cartridge length of 3.6 inches. Full length magnums have generally adhered to these dimensions ever since they were established by Holland & Holland for the .375 and .300 Magnums. This is too long to feed through a standard length bolt action; it requires an extra long "magnum length" action. Not all rifle manufacturers offer an action that will accommodate a cartridge this long, and those that do often charge a premium price for their magnum action. This has always been the primary factor limiting the popularity of the .300 H&H.
Holland & Holland also established what became the standard magnum rim diameter of .532 inch, used by virtually all magnums ever since. The SAAMI maximum average pressure limit established for the .300 H&H is 54,000 cup.
The .300 H&H is obsolescent in America, having been replaced by the shorter, more powerful (as factory loaded) .300 Winchester Magnum. For many years the standard .300 H&H factory load in the U.S. listed a 180 grain bullet at 2920 fps. Recently that muzzle velocity has been reduced to 2880 fps. The muzzle energy of the current load is 3315 ft. lb. At 200 yards the figures are 2380 fps and 2260 ft. lbs.
The trajectory of that load looks like this (Federal figures): +1.8" at 100 yards, 0 at 200 yards, and -8.0" at 300 yards. Sighting one's rifle to put the 180 grain factory loaded bullet 3" high at 100 yards would make the big .300 about a 275 yard big game cartridge.
Handloaders can easily and safely exceed the performance of the typical factory load. For the handloader, the venerable .300 H&H Magnum gives away nothing to the newer short and standard length .300 Magnums, and it is superior with the heavy 220 and 250 grain bullets. According to the Barnes Reloading Manual No. 1 their 180 grain bullets can be driven to a MV of 2904 fps in front of 65.0 grains of RL19 powder, and a MV of 3091 fps in front of 69.0 grains of RL19.
The .300 H&H can exceed the maximum velocity of the .300 Winchester Magnum by about 75 fps with the 250 grain Barnes bullet in front of a maximum load of 67.0 grains of H4831 powder. This load in the .300 Holland gave a MV of 2,650 fps vs. a MV of 2,574 fps for the top load with any powder for the .300 Win. Mag.
Copyright 2002, 2012 by Chuck Hawks. All rights reserved.