7mm STW

7 mm STW
Type	Rifle
Place of origin	United States
Production history
Designer	Layne Simpson
Designed	1979
Produced	1989-Present
Specifications
Parent case	8mm Remington Magnum
Case type	Belted, bottleneck
Bullet diameter	.284 in (7.2 mm)
Neck diameter	.315 in (8.0 mm)
Shoulder diameter	.4868 in (12.36 mm)
Base diameter	.5126 in (13.02 mm)
Rim diameter	.532 in (13.5 mm)
Rim thickness	.220 in (5.6 mm)
Case length	2.850 in (72.4 mm)
Overall length	3.60 in (91 mm)
Rifling twist	9
Primer type	Large rifle magnum
Ballistic performance
Bullet mass/type Velocity Energy 120 gr (8 g) X 3,384 ft/s (1,031 m/s) 3,052 ft·lbf (4,138 J) 140 gr (9 g) X 3,268 ft/s (996 m/s) 3,321 ft·lbf (4,503 J) 150 gr (10 g) BT 3,233 ft/s (985 m/s) 3,482 ft·lbf (4,721 J) 160 gr (10 g) Partition 3,177 ft/s (968 m/s) 3,587 ft·lbf (4,863 J) 175 gr (11 g) PSPCL 3,047 ft/s (929 m/s) 3,609 ft·lbf (4,893 J)
Test barrel length: 26" Source(s): Accurate Powder

The 7mm Shooting Times Westerner, sometimes referred to as the 7mm STW began as a wildcat rifle cartridge developed by Layne Simpson in 1979. It is an 8mm Remington Magnum case that has been "necked down" (narrowing the case opening) by 1 mm to accept 7 mm (.284 in) bullets. This cartridge is named after the magazine Shooting Times where Layne Simpson is a regular contributor.

The 7mm STW graduated to commercial status when it was officially recognized by SAAMI in 1996.Remington Arms Company was one of the first large ammunition companies to produce this cartridge in 1997, with others like Federal Cartridge Company, A-Square, and Speer also carrying it. Many US riflemakers now offer a selection of production models chambered for the 7mm STW, which has established a reputation as a fine long-range elk and large game rifle. Layne Simpson may have popularized the cartridge when he named it the 7mm STW, but he is not the first to make or use such a cartridge. Jon Herold a gunsmith from Waynesboro PA. used it in 1000 yd matches at Williamsport PA. at least 10 years before.

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Wikipedia