40 S&W

.40 S&W covers ammunition developed in the late twentieth century to bridge the gap between 9×19 mm and .45 ACP for law enforcement and defensive use. Adopted widely by police agencies during the 1990s and 2000s, the cartridge saw rapid commercial expansion and extensive experimentation in projectile design, materials, and terminal behavior.

This category includes standard ball and FMJ loads, duty and defensive cartridges, specialty and experimental projectiles, blanks, dummies, snap caps, proof rounds, and manufacturer-specific designs. Variations in bullet construction, including bonded cores, hollow points, frangible and specialty designs, along with diverse case materials and tip markings, reflect the intensive development cycle of the caliber. The breadth of examples makes this category especially useful for collectors interested in modern law enforcement ammunition, defensive handgun evolution, and late–twentieth-century cartridge innovation.