.300 H&H Magnum | ||||||||||||||||||||||||
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Type | Rifle | |||||||||||||||||||||||
Place of origin | United Kingdom | |||||||||||||||||||||||
Production history | ||||||||||||||||||||||||
Designer | Holland & Holland | |||||||||||||||||||||||
Designed | 1925 | |||||||||||||||||||||||
Manufacturer | Holland & Holland | |||||||||||||||||||||||
Produced | 1925 | |||||||||||||||||||||||
Specifications | ||||||||||||||||||||||||
Parent case | .375 H&H Magnum | |||||||||||||||||||||||
Case type | Belted, straight | |||||||||||||||||||||||
Bullet diameter | .308 in (7.8 mm) | |||||||||||||||||||||||
Neck diameter | .338 in (8.6 mm) | |||||||||||||||||||||||
Shoulder diameter | .450 in (11.4 mm) | |||||||||||||||||||||||
Base diameter | .513 in (13.0 mm) | |||||||||||||||||||||||
Rim diameter | .532 in (13.5 mm) | |||||||||||||||||||||||
Rim thickness | .220 in (5.6 mm) | |||||||||||||||||||||||
Case length | 2.850 in (72.4 mm) | |||||||||||||||||||||||
Overall length | 3.600 in (91.4 mm) | |||||||||||||||||||||||
Rifling twist | 1 in 10 in (250 mm) | |||||||||||||||||||||||
Primer type | large rifle magnum | |||||||||||||||||||||||
Maximum pressure (C.I.P.) | 54,000 psi (370 MPa) | |||||||||||||||||||||||
Maximum pressure (SAAMI) | 62,000 psi (430 MPa) | |||||||||||||||||||||||
Maximum CUP | 54,000 [1] CUP | |||||||||||||||||||||||
Ballistic performance | ||||||||||||||||||||||||
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Test barrel length: 26 in (660 mm) Source(s): Reloading data at Accurate Powder |
The .300 H&H Magnum cartridge was introduced by the British company Holland & Holland as the Super-Thirty in June, 1925. [2] The case was belted like the .375 H&H Magnum, and is based on the same case, as also is the .244 H&H Magnum. The belt is for headspace as the cases' shoulders have a narrow slope rather than an actual shoulder. More modern magnums continue this practice, but headspacing on the belt is not necessary with their more sharply angled shoulders. The cartridge was used by American shooter Ben Comfort to win the 1000-yard Wimbledon Cup Match at Camp Perry in 1935, [2] and it was used again to win the international 1,000 yard competition in 1937. [3] Winchester chambered the Model 70 in .300 Holland & Holland Magnum in 1937. [2]
The cartridge offered superior ballistics to the .30-06 for long range, and the .300 H&H is almost as versatile with all bullet weights and types, especially if well-developed handloads are used. It excels with the heaviest .30-calibre bullets in the 180–220-grain range. SAAMI has set the pressure limit for this cartridge at 54,000 P.S.I. [3] Its case length calls for a full-length magnum action, and surplus military actions chambered for the .308 Norma Magnum or the .300 Winchester Magnum offered a lower cost alternative for similar ballistics in the 1960s. [4] The long .300 H&H case was designed for loading cordite, and those two modern magnum cartridges offered similar powder volume in a shorter case better adapted to ballistic uniformity with United States Improved Military Rifle (IMR) smokeless powder. [5]
It has never been as popular as the .30-06; but the mystique of well-crafted rifles chambered for the .300 H&H keeps the cartridge in use despite its repeatedly reported demise. The .300 H&H is a fine African plains game cartridge, and suitable for all but the most dangerous big game and pachyderms.
As it was common for rimless hunting cartridges, a rimmed (beltless) variant, at the time called just "Holland's Super .30" [6] and now sometimes named .30 Super Flanged H&H, was developed simultaneously for break-barrel rifles and combination guns. [7]
The CIP treats the .300 H&H Magnum and the .30 Super Belted Rimless H&H as separate entities and provides separate entries for the cartridges. There are minute but significant variations with regard to dimensions between the two cartridges. While both cartridges are regulated by the CIP only the .300 H&H Magnum's chamber is regulated by the CIP. The CIP does not provide chamber dimensions for the .30 Super. Although cartridges are generally considered interchangeable, chambers conforming to the strict minimum chamber of the .30 Super may not be able to chamber the .300 H&H Magnum.
Both cartridges are based on .375 H&H Magnum cartridge design which provides an increase in capacity over many other cartridges. They feature tapering bodies and very shallow shoulders which prevent them from headspacing reliably on their shoulders. The belt plays a useful role in these cartridges in that it provides a demarcation point for reliable headspacing of the cartridge.
Dimension / Specification | CIP Dimension Index | 300 H&H Magnum Value | .30 Super Value |
Base to shoulder length | L1 | 53.46 mm (2.105 in) | 53.34 mm (2.100 in) |
Base to neck length | L2 | 62.96 mm (2.479 in) | 62.87 mm (2.475 in) |
Height to belt | E | 5.59 mm (0.220 in) | 5.56 mm (0.219 in) |
Extractor notch ∅ | E1 | 11.94 mm (0.470 in) | 11.61 mm (0.457 in) |
Extractor notch width | e min | 0.94 mm (0.037 in) | 1.02 mm (0.040 in) |
∠ to belt | δ | 35° | 45° |
Shoulder ∠ | α | 17° 0’ 9” | 16° 56’ 59” |
Pressure | Pmax | 4,300 bar (62,000 psi) | 3,650 bar (52,900 psi) |
Significantly the shoulder vertex calculated by the CIP for both cartridges is given as 91.69 mm (3.610 in) for both cartridges. As the CIP uses the shoulder vertex length as an index to provide correct headspacing for the cartridge, this indicates that the cartridges are dimensionally interchangeable. However, as the .30 Super is rated for a lower pressure, the .300 H&H Magnum cartridge should not be fired in a .30 Super. However, the .30 Super can be discharged in a .300 H&H Magnum rifle. As most significant difference between the cartridges was that the .30 Super was loaded to a far lower pressure than the .300 H&H Magnum. The .30 Super drove a 180 gr (12 g) bullet at 2,750 ft/s (840 m/s) while the .300 H&H Magnum was loaded with the same bullet at 2,920 ft/s (890 m/s).
The .357 SIG is a bottlenecked rimless centerfire handgun cartridge developed by the Swiss-German firearms manufacturer SIG Sauer, in cooperation with ammunition manufacturer Federal Premium. The cartridge is used by a number of law enforcement agencies.
In firearms, headspace is the distance measured from a closed chamber's breech face to the chamber feature that limits the insertion depth of a cartridge placed in it. Used as a verb by firearms designers, headspacing refers to the act of stopping deeper cartridge insertion. The exact part of the cartridge that seats against the limiting chamber feature differs among cartridge and gun designs. In general, bottleneck rifle cartridges headspace on their case shoulders; rimmed cartridges headspace on the forward surfaces of their case rims; and rimless pistol cartridges headspace on their case mouths. The case belts on belted cartridges were originally added to allow headspacing on the belt's forward surface, but in practice this is often vestigial and rifles chambered in belted cartridges may well headspace them on their shoulders.
The .308 Winchester is a smokeless powder rimless bottlenecked rifle cartridge widely used for hunting, target shooting, police, military, and personal protection applications globally. It is similar but not identical to the 7.62×51mm NATO cartridge.
The .460 Weatherby Magnum is a belted, bottlenecked rifle cartridge, developed by Roy Weatherby in 1957. The cartridge is based on the .378 Weatherby Magnum necked up to accept the .458-inch (11.6 mm) bullet. The original .378 Weatherby Magnum parent case was inspired by the .416 Rigby. The .460 Weatherby Magnum was designed as an African dangerous game rifle cartridge for the hunting of heavy, thick skinned dangerous game.
A rim is an external flange that is machined, cast, molded, stamped, or pressed around the bottom of a firearms cartridge. Thus, rimmed cartridges are sometimes called "flanged" cartridges. Almost all cartridges feature an extractor or headspacing rim, in spite of the fact that some cartridges are known as "rimless cartridges". The rim may serve a number of purposes, including providing a lip for the extractor to engage, and sometimes serving to headspace the cartridge.
The .458 Winchester Magnum is a belted, straight-taper cased, Big Five game rifle cartridge. It was introduced commercially in 1956 by Winchester and first chambered in the Winchester Model 70 African rifle. It was designed to compete against the .450 Nitro Express and the .470 Nitro Express cartridges used in big bore British double rifles. The .458 Winchester Magnum remains one of the most popular large game cartridges, and most major ammunition manufacturers offer a selection of .458 ammunition.
The .257 Weatherby Magnum is a .257 caliber (6.53 mm) belted bottlenecked cartridge. It is one of the original standard length magnums developed by shortening the .375 H&H Magnum case to approx. 2.5 in (64 mm). Of the cartridges developed by Roy Weatherby, the .257 Weatherby Magnum was known to have been his favorite, and the cartridge currently ranks third in Weatherby cartridge sales, after the .30-378 Weatherby Magnum and the .300 Weatherby Magnum.
The .375 H&H Magnum also known as .375 Holland & Holland Magnum is a medium-bore rifle cartridge introduced in 1912 by London based gunmaker Holland & Holland. The .375 H&H cartridge featured a belt to ensure the correct headspace, which otherwise might be unreliable, given the narrow shoulder of the cartridge case. The cartridge was designed to use cordite which was made in long strands – hence the tapered shape of the case, which, as a beneficial side effect also helped in smooth chambering and extraction from a rifle's breech.
The .338 Winchester Magnum is a .338 in (8.6 mm) caliber, belted, rimless, bottlenecked cartridge introduced in 1958 by Winchester Repeating Arms. It is based on the blown-out, shortened .375 H&H Magnum. The .338 in (8.6 mm) is the caliber at which medium-bore cartridges are considered to begin. The .338 Winchester Magnum is the first choice among professional brown bear guides in Alaska to back up clients where a powerful stopping caliber is required on charging bears. It is also the most popular medium-bore cartridge in North America and has the most widely available choice in rifles among medium bore rifles. The action length is the same as a .30-06, and most major rifle manufacturers in the United States chamber rifles for the cartridge including the semi-automatic Browning BAR Mk II Safari, making it a very powerful combination against charging dangerous game. The cartridge was intended for larger North American big-game species and has found use as for the hunting of thin-skinned African plains-game species.
The 7mm Remington Magnum rifle cartridge was introduced as a commercially available round in 1962, along with the new Remington Model 700 bolt-action rifle. It is a member of the belted magnum family that is directly derived from the venerable .375 H&H Magnum. The original purpose of the belted magnum concept taken from the .300 H&H Magnum and .375 H&H Magnum, was to provide precise headspace control, since the sloping shoulders, while easing cartridge extraction, were unsuitable for this purpose. Improved cartridge extraction reliability is desirable while hunting dangerous game, in particular when a fast follow-up shot is required. The 7mm Remington Magnum is based on the commercial .264 Winchester Magnum, .338 Winchester Magnum, and .458 Winchester Magnum, which were based on the same belted .300 H&H Magnum and .375 H&H Magnum cases, trimmed to nearly the same length as the .270 Weatherby Magnum.
The .35 Whelen is a powerful medium-bore rifle cartridge that does not require a magnum action or a magnum bolt-face. The parent of this cartridge is the .30-06 Springfield, which is necked-up to accept a bullet diameter of .358 in (9.1 mm). This cartridge is more powerful than its parent, especially in killing power on large game. However, with much wider availability, and the higher BC .30 caliber bullets of today, the power gap between the two cartridges has been decreased.
The .300 Remington Ultra Magnum, also known as the .300 Ultra Mag, 7.62×72mm or .300 RUM is a 7.62 mm rifle cartridge introduced by Remington Arms in 1999. The .300 Remington Ultra Magnum is one of the largest commercially available .30 caliber magnums currently being produced. It is a beltless, rebated rim cartridge, capable of handling all large North American game, as well as long-range shooting. Among commercially produced .30-caliber rifle chamberings, the .300 Remington Ultra Magnum is second only to the .30-378 Weatherby Magnum in cartridge-case capacity.
The .416 Remington Magnum is a .416 caliber (10.57 mm) cartridge of belted bottlenecked design. The cartridge was intended as a dangerous game hunting cartridge and released to the public in 1989. The cartridge uses the case of the 8 mm Remington Magnum as a parent cartridge. When the cartridge was released in 1988, author Frank C. Barnes considered the .416 Remington Magnum to be the "most outstanding factory cartridge introduced in decades".
The .375 Ruger (9.5×65.5mm) is a rimless, standard-length rifle cartridge designed for the hunting of large, dangerous game. It is designed to provide an increase in performance over the .375 H&H cartridge, yet to be chambered in a standard-length action rifle. The cartridge was designed in partnership, by Hornady and Ruger. In 2007, it was released commercially and chambered in the Ruger Hawkeye African and the Ruger Hawkeye Alaskan rifles.
The .325 Winchester Short Magnum, commonly known as the 325 WSM is an 8mm caliber rebated rim bottlenecked centerfire short magnum medium bore cartridge. The cartridge was introduced by Winchester Ammunition in 2005.
The 6.5mm Creedmoor (6.5×48 mm), designated 6.5 Creedmoor by SAAMI, 6.5 Creedmoor by the C.I.P. or 6.5 CM or 6.5 CRDMR for short, is a centerfire rifle cartridge introduced by Hornady in 2007. It was developed by Hornady senior ballistics scientist Dave Emary in partnership with Dennis DeMille, the vice-president of product development at Creedmoor Sports, hence the name. The cartridge is a necked-down modification of the .30 Thompson Center.
The .458 Lott is a .458 caliber rifle cartridge designed for the purpose of hunting large, thick-skinned dangerous game animals in Africa. It is based on the full length .375 H&H Magnum case blown out and shortened to 2.800 inches (71.1 mm).
The .275 Holland & Holland Magnum is a semi-obsolete rifle cartridge similar to the 7mm Remington Magnum. Essentially the .275 Holland & Holland Magnum is a necked down shortened variant of the .375 Holland & Holland Magnum. It was introduced by the British company Holland & Holland with the .375 Holland & Holland Magnum that was introduced in 1912 as the .375 Belted Rimless Nitro-Express. The .375 Holland & Holland Magnum was intended for dangerous African game animals, while the .275 Holland & Holland Magnum was intended for longer range shooting of antelope in Africa and Red Stag in the highlands of Scotland.
.30-06 Springfield wildcat cartridges are cartridges developed from a 30-06 Springfield "parent cartridge" through narrowing or widening the cartridge neck to fit a smaller or larger bullet in an attempt to improve performance in specific areas. Such wildcat cartridges are not standardized with recognized small arms standardization bodies like the SAAMI and the CIP.
The .300 Ruger Compact Magnum or .300 RCM is a rimless, short-length rifle cartridge designed for the hunting of Medium-to-Large-sized North American game.
The .300 Holland & Holland Magnum by Chuck Hawks (subscription req)