The .300 Win Mag definitely falls into the long-distance cartridge category, but it also encompasses some very favourable properties, making it a superb all-round calibre. It has no shortage of followers, counting our own editor and Mike Yardley among them.
Launched some 38 years before the Winchester, the highly respected .300 H&H Magnum had covered similar ground, seeing widespread use across Africa and winning the 1,000-yard Wimbledon Cup in 1935. The blown out and shortened case of the .300 Win Mag sports a much steeper shoulder than the .300 H&H. The body of the case was stretched by some 0.12in over equivalent calibres, and although unconfirmed, it was speculated that Winchester oversized the case to allow rifles already chambered in .30-338 and .308 Norma to be easily reamed out to fit .300 Win Mag dimensions.
In any event, the .300 Win Mag has seen global success, seeing extensive use as the calibre of choice for those reaching shots required on antelope in the open plains, or cross-canyon targeting for perilously perching sheep and goats. It truly is an excellent sheep calibre, if not the best. Equally, it provides adequate energy to cope with the biggest bears, pushing a 180-grain bullet with 3,500ft/lb muzzle energy. It also exhibits more than acceptable varminting capabilities, using the flat-shooting 130-grain head (rising just 0.9in for a 200-yard zero, with a five-inch drop to 300 yards).
Today it is hard not to feel that the calibre has been outclassed ballistically by the .300 Weatherby Magnum and more recently the .300 Rem Ultra Magnum. The numbers are quite telling. Taking the same 180-grain bullet with factory loads in all three calibres, we see the .300 Rem Ult Mag drop 5.6in at 300 yards, compared to 6.2in and 7in for the Weatherby and Winchester respectively (based on a 200-yard zero). Over 400 yards the Remington trumps the Winchester by over four inches, delivering considerably more down-range energy at 2,400ft/lb – 200ft/lb more than the Weatherby and 600ft/lb more than the Winchester.
This all sounds great in theory, but the laws of physics mean you can’t squeeze out all that performance without having to pay for it. The equal and opposite reaction to this down-range magic is felt by the shooter in the form of some seriously unpleasant recoil. Unless you enjoy feeling like you have been worked over with an iron bar the morning after, this will not be the rifle to take for a date at the shooting range.
So where does this leave the .300 Win Mag? Although it appeared to have been swept away by the new-fangled cool kids on the block, this owed more to testing on paper than in the field. Given a 260-yard zero, the .300 Win Mag will still shoot inside a six-inch kill zone out to 300 yards. You will gain a few more yards with the Ultra Mag, sure, but even at out at 350 yards we are only talking a 1.5in advantage. Serious advantage is only seen in ultra-long range shots, which have questionable ethics at any rate. The .300 Win Mag provides an excellent compromise, with a level of accuracy that was never in question. BP