Starline 40 SW Brass Cases (Small Pistol Primer) 40 S&W Brass, 40 Smith & Wesson Brass, 40 Smith Brass, 40 Cal Brass, 40 Caliber Brass, 40S&W Brass The .40 S&W is basically a short version of the 10mm Auto that utilizes the Small Pistol primer. This cartridge quickly became a favorite among Law Enforcement, target shooters, and plinkers due to its combination of accuracy, power, low recoil and availability. O.A.L.: 0.842-0.847 100 count by weight