Weatherby Mark V Backcountry 6.5 RPM

But Weatherby Didn’t …

“We set out to develop a cartridge that would fit in our slim six-lug Mark V action, but take full advantage of every bit of space,” said Weatherby’s chief, Adam Weatherby. “Our engineers came up with a flat-shooting 6.5 that sends a 127-gr. bullet at over 3,200 fps and a 140 at over 3,000.” With nearly a ton-and-a-half of energy at the muzzle, those bullets carry 1,500 ft-lbs. nearly 500 yards!

The new 6.5 Weatherby RPM (Rebated Precision Magnum) differs from the company’s signature cartridges in several ways. It has no belt. Like the .284 Winchester of 1963, its body is bigger in diameter than its .473 rim, which fits standard bolt faces. Unlike the .284, developed for short rifle actions (also the 6.5/284 wildcat Norma adopted in 2002), the RPM case is 2.60 long, 0.10 longer than the brass of most belted cartridges for .30-06-length actions. Result: magnum powder capacity without the bolt head and heavy action of a rifle built for the spawn of the .300 H&H or .404 Jeffery. The 6.5 RMP is a perfect fit for Weatherby’s nimble six-lug Mark V series, first produced stateside in 1996.

Another RPM departure — Junctures of its 35-degree shoulder are not radiused. Roy Weatherby’s early case designs owe much to fellow California wildcatter R.W. Miller, who in 1940 was working with the .300 Hoffman and experimenting with radiused shoulders. The American Rifleman’s E. Baden Powell suggested limiting bolt thrust by reducing case taper. The resulting case design was called PMVF: Powell Miller Venturi Freebore. In 1944 the two men went into business — a year later they sold out to Hollywood Tool and Die. After Roy carried a .270 PMVF on a hunt, he wanted the same profile for Weatherby cartridges. Miller demurred. Enter George Fuller, who had made the reamer for the .220 Weatherby Rocket.