The 7mm WSM and 7mm Rem. SAUM
By Chuck Hawks
Remington and Winchester went to short, fat, unbelted cases for their latest 7mm magnums, the 7mm Remington Short Action Ultra Magnum and the Winchester Short Magnum. Both cartridges were designed to work through short action rifles. Both were introduced in 2001.
Remington claims that the ballistics of the 7mm SAUM equal those of the popular 7mm Rem. Mag., and exactly the same claim is made for the 7mm WSM. These claims are valid if the short magnum cartridges are fired in 24 inch barrels, the same length as the barrels of most 7mm Rem. Mag. rifles. In shorter barrels, performance declines dramatically.
Winchester claims a muzzle velocity (MV) of 3,225 fps with a 140 grain bullet for their 7mm WSM cartridge; the claimed muzzle energy (ME) is 3,233 ft. lbs. With a 160 grain bullet the Winchester figures are 2990 fps and 3176 ft. lbs. at the muzzle. The lighter, shorter 7mm bullets are preferred in these short case magnums.
Remington claims a MV of 3175 fps and ME of 3133 ft. lbs. for their 7mm SAUM with a 140 grain bullet. With a 160 grain bullet the Remington figures are 2960 fps and 3112 ft. lbs. at the muzzle. All of the figures from both companies were developed in 24 inch test barrels.
Medium slow burning rifle powders are most appropriate for both of these cartridges. RL-19, H4350, and IMR 4350 are all good choices.
Here are some specifications of interest to those reloading the 7mm SAUM cartridge: bullet diameter .284", maximum COL 2.825", maximum case length 2.035".
Reloading data published in the fifth edition of the Nosler Reloading Guide for the 7mm Rem. SAUM shows that 56.0 grains of IMR 4350 powder will drive their 140 grain bullets to a MV of 2943 fps, and 60.0 grains of IMR 4350 is good for a MV of 3146 fps. IMR 4350 was the most accurate powder tested. The Nosler loads were developed in Remington cases with Remington primers, and chronographed in a 24 inch barrel.
Here are some specifications of interest to those reloading the 7mm WSM cartridge: bullet diameter .284", maximum COL 2.860", maximum case length 2.100".
Hodgdon reloading data for the 7mm WSM shows that the 140 grain Nosler Partition spitzer bullet can be driven to a MV of 2979 fps in front of 58.0 grains of H4350 powder. The maximum load for that bullet is 61.5 grains of H4350 powder, which yields a MV of 3133 fps at a chamber pressure of 61,900 psi. The Hodgdon technicians used Winchester cases and primers to develop their loads, and they were chronographed in a 24 inch barrel.
Note: A full length article about the 7mm WSM and 7mm Rem. SAUM can be found on the Rifle Cartridge Page.
Copyright 2004, 2013 by Chuck Hawks. All rights reserved.