Testing with a variety of ammunition proved the USP meets these high standards. During the USP testing phase, the recoil-reduction system reduces the force on the USP grip to approximately 300 newtons (67 pounds-force). Peak force shock on competing .40 caliber polymer and metal framed pistols was around 5,000 newtons (1,100 pounds-force). The primary benefit of low peak shock is a decrease in wear and tear on pistol components, a great concern with the +P cartridge in 9 mm, .40 S&W, and .45 ACP. Reduction of peak shock forces also contributes to softer recoil for the shooter, although these "felt recoil" values are subjective.