The 7mm Shooting Times Westerner (STW) was designed in 1979 by Layne Simpson as a wildcat cartridge and produced for the commercial market starting in 1989. The 7mm STW is based off the parent case 8mm Remington Magnum with a narrowed neck to fit a .284 inch bullet on a .315 inch neck. It has a large rifle magnum primer and a case length of 2.850 inches with overall length of 3.60 inches.
The ballistic performances based off five grain types for the 7mm STW on a 26 inch test barrel for muzzle velocity are 3,384 ft/s (120 gr), 3,268 ft/s (140 gr), 3,233 ft/s (150 gr), 3,177 ft/s (160 gr), and 3,047 ft/s (175 gr). The 7mm STW was first cartridge named for a gun magazine (Shooting Times Magazine) and Layne Simpson was the editor of STM at the time 1979.
Hand loading brass is available for the 7mm STW in a variety of loads. The muzzle velocity for performances are 3,200 ft/s (160 gr Spitzer w/69.0 grains of RL22 powder), and 3,121 ft/s (160 gr Spitzer w/73.0 grains of RL22 powder). The drop-off in trajectory and wound penetration occurs at approximately 335 yards distance. The 7mm STW is used by hunters for medium sized game and can also take down large sized game depending on the grain size bullet used.
Remington created the 7mm Remington Ultra magnum in 2000 based on the.300 Remington Ultra Magnum, which is also based on a heavily modified version of the unbelted 404 Jeffery's case from 1999. The 7mm RUM was created to deliver ultra-high velocity in order to address the increasing demand for long-range hunting rifles and ammunition.
The 7mm RUM has gained a small following among long-range hunting fans since its release. However, because of the limited barrel life, it is a chambering that most hunters eventually abandon. Its barrel life is exceptionally short due to hot gas degradation at the commencement of the rifling, the finely carved lead that guides the bullet into full bore engagement. When used in the same way as a conventional hunting or target cartridge, the barrel life is usually around 600 rounds.
Remington engineers created a chamber design with a .400 inch (10mm) free bore to improve the performance of the 7mm RUM. Because of the longer pressure curve, this free bore functions as a gas expansion chamber, maximizing velocity. The case is built for a working pressure of 65,000psi, however, brass is brass, therefore the case life is limited.
Difficulties aside, and where accuracy allows, the 7mm RUM is a fantastic medium game performer, generating extremely emphatic kills out to 800 yards and clean kills out to and beyond 1000 yards, at which range pace of death is dependent on target resistance to aid bullet expansion. The 7mm RUM often fails to induce hydrostatic shock at point-blank ranges, resulting in a dead running game. This sort of performance may be extremely frustrating for mountain hunters, who are losing the dead run game to ravines.
