7mm Weatherby Magnum (using Hornady bullets)
Date: Mar 29 2016
The 7mm Weatherby Magnum dates back to around 1943/44 when Roy Weatherby began blowing out the shoulder and necking down the belted .300 H&H Magnum case to several calibers. This was almost 20 years prior to the 7mm Remington Magnum and 10 years before the 7x61 Sharpe & Hart Super was developed. It not only outperformed those two magnums, but all other commercially available 7mm’s of that period. Sales for the 7mm Weatherby Magnum have always been overshadowed by the popularity of the .300 Weatherby Magnum. Regardless, the 7mm is an excellent cartridge that offers flat trajectory, long-range accuracy, and with correct bullets is suitable for all North American game and African plains game.
Current Weatherby factory loads include the Hornady 154-grain SP bullet advertised at 3,260 fps (26-inch barrel), but clocked 3,228 fps. The Nosler 160-grain Partition is advertised at 3,200 fps, but clocked 3,184 fps from a test rifle.
In 1994 the 7mm Weatherby Magnum became a standard industry cartridge with a maximum average pressure of 65,000 psi. This change invited other ammunition companies to begin offering loads. Federal cases have less powder capacity than the Weatherby case (as well as Nosler Custom cases) and were used to develop the accompanying data. It is therefore suggested to reduce powder charges in the accompanying data by 1.5 to 2.0 grains when using Federal cases.
Using a newly manufactured Weatherby Mark V test rifle with a 26-inch barrel many loads proved capable of sub-MOA, and select loads grouped under .5 inch.
With Hornady 120-grain V-Max bullets, selected loads reached 3,400 to 3,500 fps. The various 139-grain Hornady bullets are popular for hunting deer, however, at velocities that can exceed 3,300 fps they can be very destructive. The 154- and 162-grain bullets are generally the best general-purpose deer bullets.
Several powders worked well including Alliant Reloder 19, 22, and 25; IMR 4350, 4831 and 7828; Accurate AAC-4350; Vihtavuori N-160 and N-165; Hodgdon H-4350, H-4831 and H-1000.