Ammo Brief: 7mm Weatherby Magnum

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Here we take a quick look at 7mm Weatherby Magnum, an unfortunate victim of the 7mm Remington Magnum.

The 7mm Weatherby Magnum was developed in 1944 as one of a series of cartridges based on the necked-down .300 H&H case (it is the .270 WM necked up .007 inch, although it does use a longer overall cartridge length). There are several similar wildcat versions, but Weatherby’s design is the most popular, due to the availability of commercial ammunition.

General Comments

The 7mm (or .284-caliber) has long been popular in the United States in various wildcat cartridges, yet the original 7mm Mauser never generated any great enthusiasm. The 7mm Weatherby Magnum, offered as a maximum-performance cartridge, is probably the best known and most widely used of the current 7mm Magnums, with the single exception of the 7mm Remington Magnum. This is due in part to the availability of factory-loaded ammunition in a good selection of bullet weights.

The 7mm Weatherby has a slight edge over the .270 Weatherby on tough or dangerous game because it can use heavier bullets and churns up greater energy. However, if long-range varmint shooting is on the agenda, the .270 is the better choice. The 7mm Weatherby Magnum is adequate for any North American big game and all thin-skinned African game. The 7mm Weatherby Magnum has, to a large extent, lost popularity to the 7mm Remington Magnum, because the Remington version is available in a wider variety of rifles that are generally less expensive than the Weatherbys.

Like most high-intensity cartridges, the 7mm WM can be somewhat hard on its barrel, especially with either careless shooting, inadequate barrel cooling between shots, or inadequate barrel cleaning. And, like all similar chamberings, it loses significant velocity with barrels shorter than 24 inches. Ammunition for this cartridge is now available from Federal and Norma, as well as Weatherby.

7mm Weatherby Magnum Loading Data and Factory Ballistics

Bullet (grains/type)	Powder	Grains	Velocity	Energy	Source
100 HP	IMR4350	73.5	3,600	2,878	Hornady
115 HP	IMR4831	76	3,600	3,310	Speer
120 SP	IMR4350	70	3,400	3,081	Sierra, Nosler, Hornady
130 SP	IMR4320	63	3,300	3,144	Speer
139 SP	IMR4350	68	3,200	3,161	Sierra, Nosler, Hornady
154 SP	IMR4350	67	3,100	3,287	Hornady
160 SP	IMR4350	65	3,000	3,198	Sierra, Speer
175 SP	IMR4350	65	2,800	3,047	Speer, Hornady
195 SP	IMR7828	61	2,500	2,707	Speer
140 Barnes TSX	FL	–	3,250	3,284	Weatherby B7MM140TTSX
160 Speer Trophy Bonded	FL	–	3,100	3,414	Federal P7WBTT1
170 Oryx JSP	FL	–	2,985	3,364	Norma 20171072
175 JSP	FL	–	3,070	3,662	Weatherby H7MM175SP

Editor's Note: This article is an excerpt of Gun Digest's Cartridge's Of The World.

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