Case Histories:270 Winchester Short Magnum
- By Wheelwrite
- 1 Comments
- Last updated: 25/09/2017
I’m old, grumpy and cynical. I guess that’s why I have a rather jaundiced view of some of the ‘new’ cartridge offerings from the major ammunition manufacturers. The 270 WSM (Winchester Short Magnum, without a decimal point) surfaced just 16 years ago and owes its case history to the 300 WSM, launched just a year earlier. It was heralded as a ‘more for less’ improvement on the venerable but still very popular .270 Winchester, producing more performance from a shorter action. And to be fair, the 270 WSM (amongst the whole family of WSMs) has received the most favourable reception from the hunting community. It became only the fourth commercial cartridge to employ a .277 diameter pill, the others being the .270 Win, 6.8 Remington SPC and the best of the bunch (IMHO), the potent .270 Weatherby Magnum.
On the range, my hands-on experience of the cartridge is really limited to a press day in Nevada about a decade ago. It had a pretty sharp recoil but not much greater than the stock .270 Win. At our demo test range of 300 yards, it was remarkably flat shooting. I seem to recall that the rifle was a Winchester Model 70 Featherweight.
The WSM series are visually distinctive – the sumo wrestlers of the commercial cartridge world. All having a fat, lightly tapered barrel body, 35° shoulder, calibre length neck and marginally rebated rim. All of these features reflecting the long established accurising principles espoused by benchrest and other precision specialists. Intended for use by American hunters of domestic game such as deer, bear, antelope and sheep, it soon proved to be an impressively accurate design. Not that all of the design features are an improvement upon the older .270 Win. The extremely generous case capacity does not lend itself to the use of the lightest bullets/loads as the resulting loading density drops significantly. Nor does it work well with the heaviest .277 pills as the short case and minimalist neck place the base of such bullets inside the case body void. Optimum bullet weights are therefore bracketed around the 140/150-grain designs.
In both the press and web there are enough independent stories of stiff or sticky bolts associated with the use of factory and reloaded ammo to undermine any claim that they’re apocryphal. The latest data file from SAAMI (Z299-4_ANSISAAMI_ CFR.pdf) has yet to include pressure data for this cartridge, but it is undoubtedly very high, a fact reflected by the robust case structure. It’s therefore a given that chamber hygiene and detailed attention to reloading parameters are essential.
Despite the limited number of cartridges using the .277 pill, the choice of weight and brand is good… a legacy of the .270 Winchester cartridge. Data, brass, dies and other materials are listed by most of the usual makers. However, the modest selection of commercial ammo brands is all designed with hunting in mind.
The 270 WSM comfortably meets the specs for UK deer hunting and does facilitate the use of a relatively compact rifle. However, it really is hard to justify its selection. Overkill would be the best description. As for benchrest accuracy, Vince Bottomley has established some remarkable results with the WSM platform, albeit in 7mm. Sadly, the limiting factor in chasing ultimate accuracy in 270 may well the lack of suitable bullets!