.351 Winchester Self-Loading

.351 Winchester Self-Loading
From left to right: .35 Winchester Self-Loading, .351 Winchester Self-Loading, .45 ACP
Type	Rifle
Place of origin	United States
Service history
Used by	France United Kingdom Russia United States
Wars	World War I
Production history
Designer	Winchester Repeating Arms Company
Specifications
Bullet diameter	0.352 in (8.9 mm)
Neck diameter	0.373 in (9.5 mm)
Shoulder diameter	straight
Base diameter	0.377 in (9.6 mm)
Rim diameter	0.407 in (10.3 mm)
Rim thickness	0.05 in (1.3 mm)
Case length	1.375 in (34.9 mm)
Overall length	1.906 in (48.4 mm)
Rifling twist	1 in 16
Primer type	Small rifle
Maximum pressure	37,000 to 39,000 PSI
Ballistic performance
Bullet mass/type Velocity Energy 180 gr (12 g) 1,870 ft/s (570 m/s) 1,400 ft·lbf (1,900 J)
Test barrel length: 20 Source(s): Whelen, Townsend. The American Rifle. Century Co. 1918. p. 266.

The .351 Winchester Self-Loading (also called .351 SL or .351 WSL) is an American rifle cartridge.

Winchester introduced the .351 SL in the Winchester Model 1907 self-loading rifle as a replacement for the Winchester Model 1905 and the .35 SL. The .351 SL proved popular with police and security forces as the only chambering available in the model 1907, and was used by France in both world wars. An experimental Thompson submachine gun was also made to fire .351 SL in 1919, but was never produced commercially.

While some writers in the 1960s considered the .351 SL inadequate as a deer round, its killing power is very similar to the original loadings of the 30-30 and has similar energy at the muzzle as 35 Remington does at approximately 75 yards—pushing a 180 grain largish diameter (35 caliber) jacketed soft nose bullet at nearly 1900 fps. It has had some popularity in the jungle, where its lack of long-range power or accuracy are less important. When first introduced, many found the .351 SL to be a good deer cartridge at ranges under 200 yards, at least in comparison to the many low-pressure cartridges of the black powder era. Some of the things leading to the commercial death of the cartridge were its unusual bullet diameter (.351 vs all the other 20th century 35 caliber rifle and handgun cartridges which are .357 or .358) and the unusual rebated rim design of the case.