American Rifleman - March 2015 - (Page 52)

THE .270 WEATHERBY According to Weatherby: The Man. The Gun. The Legend. by Grits and Tom Gresham, "By the time he started in business [1945], Roy had developed the .220 Rocket (based on the .220 Swift cartridge, with a changed taper and shoulder), the .257, .270, and .300 Weatherby Magnums." Given the popularity of the .270 Win. at the time (and even now), it's little wonder that the first of his proprietary magnum cartridges-developed in 1943-was a .270, too; however, his creation was a radical departure from normalcy. Weatherby first shortened the belted, .300 H&H Mag. case and greatly reduced its taper, thereby amassing additional space for propellant. Nosler Reloading Guide No. 7 reveals that the .270 Weatherby Magnum's case capacity is approximately 82.0 grs. of water, which is about 17.4 grs. more than that of the Winchester cartridge. Next, he gave it an unusual, double-radius Venturi shoulder design, which, according to weatherby.com, "Increases the velocity of escaping gases without increasing the pressure within the cartridge, [and thus] results in higher velocity within standard pressure ranges." Interestingly, whereas the .270 Winchester's SAAMI-assigned maximum average pressure (MAP) is 65,000 p.s.i., once "adopted" in 1994, the .270 Weatherby Magnum's MAP was set at 62,500 p.s.i. Delving deeper, the .270 Win. has a maximum case length of 2.540", so the .270 Wby. Mag. at 2.549" is ever so slightly longer. Moreover, while the .270 Win.'s cartridge overall length (COL) is 3.340", its Weatherby counterpart is a shorter 3.295". The COL alone was instrumental in Weatherby's initial success, as it was a relatively simple procedure to re-chamber an existing .270 Win.-chambered rifle for his brainchild; in fact, the process only required re-reaming the chamber and altering the bolt face diameter (0.473" to 0.532") and the magazine. Weatherby offered similar conversions from .300 H&H Mag. to his potent .300 Wby. Mag. The aforementioned case characteristics all contributed to Weatherby achieving his vision, as when loaded with identical bullets, the .270 Wby. Mag.'s velocities bettered those of the Winchester by 150 f.p.s. to 400 f.p.s., depending on the projectile's weight. The cartridge design alone was insufficient to achieve said velocities, however; Weatherby also had to extend the rifling-free "throat," or "free bore," considerably, thereby enabling greater velocity potential without excessive pressure. Currently, weatherby.com lists the freebore length of .270 Wby. Mag.-chambered Mark V rifles as measuring 0.378". Additionally, typical barrel lengths were 26" or longer, which permitted better consumption (or a more complete burn) of the propellant. As previously mentioned, Weatherby desired "total disintegration" of the bullet. As cited in Gresham, in a letter to gun writer Sam Fadala, Weatherby wrote, "I am one who wants that bullet to completely disintegrate inside an animal's body. It seems to do more damage, by far, than just normal expansion." Given the standard "cup-and-core" construction of the majority of the projectiles available at that time (and even today), significant weight loss, if not outright disintegration, was relatively easily achieved at velocities approaching 3000 f.p.s.; however, Weatherby's hotrod .270 eclipsed that number by a significant margin. For example, factory numbers reveal that most of Weatherby's 130-gr., .270 Wby. Mag. loads typically attain in excess of 3300 f.p.s. In comparison, bullets of identical weight fired from a .270 Win. achieve around 3100 f.p.s. Weatherby's views on high-velocity impacts and the .270 Wby. Mag. weren't based on conjecture either, but rather on experience. For example, as detailed in Gresham, on June 14, 1948, Weatherby wrote, "Doctor shot his waterbuck, a fine one, too, with my .270 Magnum, about 150 yards. The waterbuck went down with a shoulder shot. When we skinned this fellow out, one could hardly imagine an Essentially, the .270 field of chamberings is comprised of (l. to r.), the .270 Win., the .270 WSM and the .270 Wby. Mag. The latter cartridge still remains the fastest. 52 MARCH 2015 AMERICAN RIFLEMAN http://www.weatherby.com http://www.weatherby.com

American Rifleman - March 2015

Table of Contents for the Digital Edition of American Rifleman - March 2015

Contents
American Rifleman - March 2015 - CW1
American Rifleman - March 2015 - CW2
American Rifleman - March 2015 - Cover1
American Rifleman - March 2015 - Cover2
American Rifleman - March 2015 - 1
American Rifleman - March 2015 - Contents
American Rifleman - March 2015 - 3
American Rifleman - March 2015 - 4
American Rifleman - March 2015 - 5
American Rifleman - March 2015 - 6
American Rifleman - March 2015 - 7
American Rifleman - March 2015 - 8
American Rifleman - March 2015 - 9
American Rifleman - March 2015 - 10
American Rifleman - March 2015 - 11
American Rifleman - March 2015 - 12
American Rifleman - March 2015 - 13
American Rifleman - March 2015 - 14
American Rifleman - March 2015 - 15
American Rifleman - March 2015 - 16
American Rifleman - March 2015 - 17
American Rifleman - March 2015 - 18
American Rifleman - March 2015 - 19
American Rifleman - March 2015 - 20
American Rifleman - March 2015 - 21
American Rifleman - March 2015 - 22
American Rifleman - March 2015 - 23
American Rifleman - March 2015 - 24
American Rifleman - March 2015 - 25
American Rifleman - March 2015 - 26
American Rifleman - March 2015 - 27
American Rifleman - March 2015 - 28
American Rifleman - March 2015 - 29
American Rifleman - March 2015 - 30
American Rifleman - March 2015 - 31
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American Rifleman - March 2015 - 33
American Rifleman - March 2015 - 34
American Rifleman - March 2015 - 35
American Rifleman - March 2015 - 36
American Rifleman - March 2015 - 37
American Rifleman - March 2015 - 38
American Rifleman - March 2015 - 39
American Rifleman - March 2015 - 40
American Rifleman - March 2015 - 41
American Rifleman - March 2015 - 42
American Rifleman - March 2015 - 43
American Rifleman - March 2015 - 44
American Rifleman - March 2015 - 45
American Rifleman - March 2015 - 46
American Rifleman - March 2015 - 47
American Rifleman - March 2015 - 48
American Rifleman - March 2015 - 49
American Rifleman - March 2015 - 50
American Rifleman - March 2015 - 51
American Rifleman - March 2015 - 52
American Rifleman - March 2015 - 53
American Rifleman - March 2015 - 54
American Rifleman - March 2015 - 55
American Rifleman - March 2015 - 56
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American Rifleman - March 2015 - 81
American Rifleman - March 2015 - 82
American Rifleman - March 2015 - 83
American Rifleman - March 2015 - 82b
American Rifleman - March 2015 - 83b
American Rifleman - March 2015 - 82c
American Rifleman - March 2015 - 83c
American Rifleman - March 2015 - 82d
American Rifleman - March 2015 - 83d
American Rifleman - March 2015 - 82e
American Rifleman - March 2015 - 83e
American Rifleman - March 2015 - 82f
American Rifleman - March 2015 - 83f
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American Rifleman - March 2015 - 91
American Rifleman - March 2015 - 92
American Rifleman - March 2015 - Cover3
American Rifleman - March 2015 - Cover4
American Rifleman - March 2015 - CW3
American Rifleman - March 2015 - CW4
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