.401 Winchester Self-Loading
Type Rifle
Place of origin USA
Production history
Designer Winchester Repeating Arms Company
Bullet diameter .4065 in (Bad rounding hereScript error mm)
Neck diameter .428 in (Bad rounding hereScript error mm)
Base diameter .429 in (Bad rounding hereScript error mm)
Rim diameter .457 in (Bad rounding hereScript error mm)
Rim thickness 0.05 in (Bad rounding hereScript error mm)
Case length 1.50 in (Bad rounding hereScript error mm)
Overall length 2.005 in (Bad rounding hereScript error mm)
Rifling twist 1 in 14
Primer type Large rifle
Maximum pressure 37000 to 39000 PSI
Ballistic performance
Bullet weight/type Velocity Energy
200 gr (Bad rounding hereScript error g) 2,141 ft/s (Bad rounding hereScript error m/s)2,037 ft·lbf (Bad rounding hereScript error J)
250 gr (Bad rounding hereScript error g) 1,875 ft/s (Bad rounding hereScript error m/s)1,952 ft·lbf (Bad rounding hereScript error J)
Test barrel length: 20
Source(s): Whelen, Townsend. The American Rifle. Century Co. 1918 p. 266

The .401 Winchester Self-Loading (also called .401SL or .401WSL) is an American rifle cartridge.

Winchester introduced the .401SL in the Winchester '10 self-loading rifle as a supplement to the Winchester '07 and the .351SL in their offering of hi-power, self-loading rifles. The only chambering available in the Winchester Model 1910, the .401SL was used by France, Russia, and American company security forces in the First World War.[1]

The .401SL proved powerful enough for both deer and other large game at ranges under 150 yards.[2] Both 200gr and 250gr bullet weights were offered by Winchester and other ammunition manufacturers as factory loadings. With extra available detachable magazines holding 4-rounds each, the Model '10, could provide lots of firepower for the big-game hunter. This feature helped promote the use of the .401SL on dangerous game such as moose and grizzly bear in spite of the lack of controlled expansion bullet designs, which doubtlessly would have improved game-taking performance and the subsequent reputation of the .401SL cartridge.[3]

The .401 Winchester self-loading, for comparison, is comparable in "stopping power", to a .41 Remington magnum fired from a similar length barrel.

See alsoEdit


  1. Houze, Herbert G. (2003). Winchester's First Self-Loading Rifles. 'American Rifleman' Vol 151(5) p.84.
  2. Whelen, Townsend. The American Rifle. Century Co., 1918. p.274
  3. Stebbins, Henry M. Rifles, A Modern Encyclopedia. Stackpole Co., 1958. p.274

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