401.WSL Ammo.
The .401 Winchester Self-Loading (.401 WSL) cartridge is an obsolete centerfire rifle round introduced in 1910 exclusively for the Winchester Model 1910 semi-automatic rifle.
Because major ammunition manufacturers discontinued it decades ago, finding shootable factory ammunition is highly difficult and expensive. It typically requires sourcing from custom boutique loaders, buying vintage collector boxes, or handloading your own brass.
Where to Buy .401 WSL Ammo & Components. If you are looking to fire a vintage Model 1910, your best options for ammunition, custom brass, and specialized bullets include: Custom Ammunition Builders: Specialty manufacturers occasionally produce small batches of shootable, newly manufactured obsolete ammunition.
For example, Buffalo Arms loads limited runs of custom .401 WSL ammo using reformed cases and 250-grain soft-point bullets. Reed's Ammunition & Research also lists custom-loaded 200-grain soft-point ammunition. Specialty Bullets: The .401 WSL does not use standard modern .400-inch projectiles. Instead, it requires a unique .406-inch to .407-inch bullet diameter. Handloaders can find correct jacketed flat-point options through custom makers like Vollmer Precision LLC or cast lead bullets from Bear Creek Supply.
Brass Cases: Custom brass made explicitly to specification or reformed from other parent cases can sometimes be sourced from outlets like Beaks and Brass or Graf & Sons.Vintage Cartridge Collectors: If you are looking for original, period-correct Winchester boxes for a display or collection, look at specialty gun auctions or community trade pages like the Winchester Collector Swap Meet. Note: Firing vintage ammunition is generally not recommended due to the age degradation of the primers and powder.
Ballistics & Historical Background: Winchester designed the cartridge to provide a rapid-fire, semi-automatic heavy hitter capable of bringing down large North American game like deer, moose, and grizzly bear within 150 yards.