Target Sports

SPORTS STARS: BORN AGAIN MAGNUMS

Created on 15th May 2009

LAURIE HOLLAND investigates WSMs, cartridges that questioned the definition of ‘short'

Almost as soon as metallic cartridges were introduced, the race was on to produce the most efficient models as measured by MV, ME, killing power and maybe accuracy. As now, makers sought to convince punters that their latest designs offered benefits that made competitors' products, not to mention their own older designs, inferior and outdated. Three British tags for early high-performance sporting types were ‘Express' (borrowed from reduced-formation fast trains) for light bullet, high MV loads; ‘Super'; and, a name that really caught on, ‘Magnum' (from double-size bottles of Champagne). Over time, magnums became associated with very large capacity belted designs, especially in the USA.

Confusing

Another feature magnum designs had in common was considerable overall length, so that special limited-production rifle actions were needed, then unaffordable for all but rich sportsmen. Recognising this, Winchester, later Remington, developed new designs during the 1950s and 60s - successful .300", .338" and .458" models from the former company and the 7mm Remington Magnum, dimensioned to fit standard (.30-06) length actions, thereby widely described as ‘short magnums'.

But standards change and yesterday's short is today's long. Winchester and other US makers sold their .243W and .308W models so aggressively from the 1960s that the short-action rifle became the norm outside continental Europe. However, it took nearly 40 years and many technological advances before magnum-performance cartridges could appear that fitted actions designed for the 2.8" length .308W. The first was the .300WSM (Winchester Short Magnum) launched in 2000 and promoted as the new all-purpose high performance sporting cartridge, not to be confused with the 1963 vintage .300 Winchester Magnum which remained in production. The aim was to achieve the latter's ballistics which it does in Winchester factory loads (but not other companies' .300 Win Mag products or handloads). In 2002 .270 and 7mm versions followed, and a .325WSM (8mm/0.323" diameter bullet) in 2004. Further confusing the definition of short, Winchester introduced three WSSM (Winchester Super-Short Magnum) models, chopped down and smaller calibre (.22, .243 and .25") adaptations.

Short and fat

Irrespective of calibre and case-length, WSMs, WSSMs and Remington's SAUM numbers are fat, rimless designs using a rebated case-head form, all adaptations of the ancient British .404 Jeffery. The case-head diameter of 0.535" is standard ‘magnum' as set by Holland & Holland before the Kaiser's War, but the body is fatter ahead of the extractor groove at 0.555". All four WSM cases are essentially the same design using these head dimensions, minimal body taper and 35º shoulder angle; 2.100" case length (.308W 2.015"); and 2.860" OAL (.308W 2.800"), although there are variations in the lengths of the case-neck and main body. Fans make much of the short, fat form giving more efficient powder burn, but any such real benefit is negligible in field use. They do the job extremely well, although feed may be poorer than with earlier designs and magazine capacity reduced.

Short rifle actions are stiffer, lighter and have a half-inch shorter bolt throw than standard models, but some weight reduction may be offset by manufacturers beefing receivers up to cope with the high pressures and substantial bolt-thrust generated by these pocket rockets. Winchester's .270 and .300 versions are big sellers, the others a bit less so, and have become industry standards, as such adopted by most ammunition and rifle manufacturers. Conversely, Remington's less commercially successful competing Short-Action Ultra-Magnum (RSAUM) designs are only made by that company and chambered in a small number of its rifles.

Long-range

While their ability to fit compact, light sporting rifles is the short magnums' unique selling point, the downside is a resulting unsuitability for heavy (long) bullets that have to be seated deeply in the case to stay within the 2.86" OAL. Thirty calibre models are limited to 180gn, and 7mm to 160gn unless a considerable drop in performance is accepted. The OAL restriction is irrelevant to one group - F-Class and benchrest competitors using rifles with single-shot actions and long custom-throated barrels. The .300WSM can thereby handle 200-240gn high-BC VLD projectiles, and the 7mm version 175/180gn equivalents seated well out and produce impressive MVs and accuracy. Vince Bottomley's UK 1,000yd benchrest record group of 2.670" was achieved with the 7mm WSM, and a high percentage of top F Class shooters also choose it. It should be noted there may be variations from factory versions as users may choose the .270WSM case (to increase powder capacity at the expense of case-neck length), or as in Vince's example, the .300 version (for its longer neck) as starting points, the latter called the 7mm/300WSM. A very few choose the Remington SAUM for its smaller capacity case and longer neck. A great plus factor for both WSM and RSAUM users is the absence of the case-belt found on older magnums, this feature not conducive to consistency in precision-shooting.

In summary, whether in factory sporting, or custom long-range precision target shooting form, the WSM is one of the most important cartridge developments of recent years, and is here to stay.

SPORTS STARS: BORN AGAIN MAGNUMS

Related Links

HANDLOADING: A TWIST IN THE TALE

.303 BRITISH: COMPENSATION CLAIMS

MODERN MILITARY MASTERPIECES: THE BRITISH .280/30

COWBOY CLASSICS: 32/20

SPECIAL FEATURE: MADE TO MEASURE

HANDLOADING: SOMEWHERE TO TURN

COWBOY CLASSICS: .38 WCF

MODERN MILITARY MASTERPIECES: WAR AND GLORY

HANDLOADING: SLOW BURNERS

MODERN MILITARY MASTERPIECES: ASSAULT RIFLE DESIGNS

Get a copy of Sporting Rifle

SPORTS STARS: BORN AGAIN MAGNUMS

Related Links

Newsletter