The 401 Winchester Self-Loading (.401 WSL, .401 SL)

By Chuck Hawks

Winchester introduced the .401 WSL in 1910 for their Model 1910 Autoloading Rifle (actually a carbine with a 20" barrel), which was based on a slightly modified Model 1907 action. The new Model 10 was designed specifically for the larger and more powerful .401 WSL cartridge, while the Model 07 was chambered only for the .351 WSL.

The Model 10 carbine was fed from a four round, detachable box magazine, so the hunter with an extra magazine in his pocket had considerable firepower at his disposal. This ability to keep pouring lead into large animals helped the .401's reputation for lethality and made it a pretty good black bear cartridge. The Model 10 rifle remained in the Winchester line until 1936 and .401 WSL cartridges were produced until WW II interrupted the supply of civilian ammunition.

Winchester had something of a penchant for introducing unusual calibers before World War II and the .401 is one of these. Examples of other non-standard calibers (at least when they were introduced) include the .270 Win., .33 Win., .348 Win., .351 WSL and .405 Win.

The .401 WSL is based on a semi-rimmed, straight-sided case 1.50" long that uses large rifle primers. The rim diameter is .490" and the head diameter is .433". Cartridge maximum overall length is 2.005". Jacketed bullet diameter is .406" and cast bullets should be sized to .407". The maximum average pressure should not exceed 39,000 psi.

Winchester .401 WSL factory loads were offered with 200 and 250 grain jacketed soft point (JSP), round nose bullets. The muzzle velocity of the 200 grain factory load was stated to be 2135 fps with muzzle energy of 2020 ft. lbs. The 250 grain factory load produced a MV of 1870 fps and ME of 1940 ft. lbs. These figures are for a 20" barrel. Accuracy was generally regarded as only fair from Model 10 carbines.

The reloader who wants to shoot a Model 10 carbine is in for some trouble, but it can be done. .401 WSL brass is not commonly available and neither are .406" JSP bullets. It is reportedly possible to make satisfactory cases from .35 Remington brass. 240 grain lead bullets can be cast from #2 alloy using Lyman mold #410426 and 212 grain bullets from Lyman mold #41028. According to the 45th Edition of the Lyman Reloading Handbook, IMR 4227 proved to be the best overall powder for the .401.

Using a 212 grain case lead bullet, Lyman data shows a starting load of 26.0 grains of IMR 4227 for a MV of 1915 fps. The maximum load is 29.0 grains of IMR 4227 for a MV of 2074 fps.

With a 240 grain cast lead bullet and IMR 4227 powder, the starting load is 24.0 grains and the MV 1506 fps. The maximum load for that bullet is 27.5 grains for a MV of 1968 fps.

The .401 is a good short range deer and black bear cartridge along the lines of, but somewhat more powerful than, the modern .44 Remington Magnum, as it can launch bullets of similar weight and somewhat superior SD about 100 fps faster from a 20" barrel. The .401 has been used successfully on large game such as elk and moose, but today it would be considered marginal due to the comparatively poor sectional density of its bullets and their rainbow trajectory. It is best used on animals weighing not more than about 300 pounds.

History records that the .401 WSL was used to a limited extent during the Great War (WW I) by both France and Russia. It also found favor in the US with some law enforcement personnel and private security companies, although its smaller cousin, the .351 WSL, was considerably more popular for such use.

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Copyright 2009, 2012 by Chuck Hawks. All rights reserved.