Russia had reactivated some BTR-50s from storage and deployed them to Ukraine. Variants Former USSR BTR-50P (Ob'yekt 750) (1952) – The first production version with an open troop compartment. The vehicle had no integral armament, but it did have a pintle mount for a 7.62 mm SGMB medium machine gun. Early production BTR-50P models had folding ramps at the rear of the hull to enable either a 57 mm ZiS-2, a 76.2 mm ZiS-3 or an 85 mm D-44 anti-tank gun to be loaded and fired on the engine decks. The weapon could also be fired when the vehicle was afloat, but only when the water-jets were in operation. This system had one great flaw, the muzzle of the gun was usually over the open personnel compartment and as such submitted any occupants to a considerable amount of concussion and fumes. These ramps were absent in later production models. BTR-50P – Converted into an artillery portee vehicle. This version carried its gun in the crew compartment, thus placing the muzzle of the gun outside the vehicle. While seen mostly carrying the 57 mm ZIS-2 anti-tank gun, there were also two other variants of this vehicle that carried anti-aircraft (AA) weapons. ZTPU-2 (zenitnaya samokhodnaya ustanovka) – BTR-50P converted into a self-propelled anti-aircraft gun (SPAAG), armed with twin ZPU-2 14.5 mm heavy machine guns (1,280 rounds). Prototype. ZTPU-4 (zenitnaya samokhodnaya ustanovka) – A BTR-50P converted into a SPAAG armed with quadruple ZPU-4 14.5 mm heavy machine guns (2,560 rounds). Prototype. BTR-50P – Converted into a Forward Air Control vehicle with a second superstructure on top of the first. BTR-50P – Converted into an NBC reconnaissance vehicle with a second superstructure on top of the first. BTR-50P – Has a longer nose section. BTR-50PA (Ob'yekt 750M) (1954) – BTR-50P armed with a 14.5 mm KPV heavy machine gun on a pintle mount at the front of the troop compartment. BTR-50PA with its heavy machine gun mounted on the commander's cupola. BTR-50PK (Ob'yekt 750K) (K stands for krisha – "roof") (1958) – A BTR-50P fitted with an armored roof, the troops embarking and disembarking the vehicle via two rectangular roof hatches that open to either side. There is also another rectangular roof hatch at the front of the roof. It was armed with a pintle-mounted 7.62 mm SGMB medium machine gun. This variant has an NBC protection system. The vehicle had two ventilators, one