The 9×21mm Gyurza (Гюрза, Russian for "blunt-nosed viper") round is a Russian handgun round designed to defeat body armor that was developed by TsNIITochMash for its SR-1 Vektor semi-automatic pistol and SR-2 Veresk submachine gun.

The bullet has a hard sub-caliber core contained within an outer sleeve and separated from it by a polyethylene layer.

If the bullet strikes an unarmored target, it holds together to produce a wide wound channel.

If the bullet strikes an armored target, the sleeve is stripped away, and the core penetrates alone.

The 7N29 AP loading fires a 6.7 g (103 gr) bullet at 410 m/s (1,300 ft/s) with 560 J (410 ft⋅lb) of muzzle energy and will reportedly penetrate two 1.2 mm titanium plates, plus 30 layers of Kevlar, at 50 m (160 ft).