The Heckler & Koch USP ("Universal Self-loading Pistol", or Universelle Selbstladepistole) is a semi-automatic pistol manufactured and designed by the German company Heckler & Koch.
When Heckler & Koch introduced the USP in 1993, it marked the first time HK chose to incorporate many traditional handgun design elements, such as elements of John Browning's M1911, in one pistol. Two principles guided its development â€” the first being the use of molded polymer material, and the second being the creation of a "pistol paradigm".
Heckler & Koch attempted to observe the strong points of its previous successful pistols for insight as to developing "the best" pistol. Previous HK pistol innovations include the unique squeeze cocking mechanism of the Heckler & Koch P7, the precise roller-locked bolt of the Heckler & Koch P9S, and the double action-only system used by the VP70Z. In contrast to these ambitious designs, the USP uses a Browning linkless-locked breech action, similar to the action developed by John Browning for use in the Browning P35 "Hi Power" pistol. The USP can be safely carried "cocked and locked".
The USP was originally built in .40 S&W and 9 mm Parabellum models, but later evolved into a .45 ACP variant and later spawned the USP Compact series, which is available in 9 mm Parabellum, .40 S&W, .45 ACP, and, exclusively to the Compact model, .357 SIG. Other variants of the standard USP include the USP Tactical, USP Expert, USP Match, and USP Elite.
One of the most important features of the USP is the mechanical recoil reduction system. This system is incorporated into the recoil/buffer spring assembly, located below the barrel. Designed primarily to buffer the slide and barrel and reduce recoil effects on the pistol components, the system also lowers the recoil forces felt by the shooter. The USP recoil reduction system is insensitive to ammunition types and does not require adjustment or maintenance. It functions effectively in all USP models. Using this same recoil reduction system, one of the related HK MK23 .45 ACP Special Operations Pistols fired more than 30,000 +P cartridges and 6,000 proof loads without damage to any major components. Abuse and function-testing of USPs have seen more than 24,000 rounds fired without a component failure.
Major metal components on both the USP and Special Operations Pistol are corrosion-resistant. Outside metal surfaces, such as the steel slide are protected by a nitro-gas carburized black oxide finish. Internal metal parts, such as springs, are coated with an anti-corrosion chemical to reduce friction and wear.
The USP is the base of the Mk 23 Mod 0, a .45 ACP handgun designed by Heckler & Koch for the USSOCOM. The frame and slide of the USP45 are slightly larger than those found on the USP40 and USP9, much like the Mk 23. The prominent oversized trigger guard allows the use of gloves when firing.