As mentioned previously, the “cannon” is actually a 14.5mm (about .60 caliber) KPV heavy machine gun, designed by Vladimirov in Russia, but manufactured around the world in the former East Block countries and their one-time allies (like Egypt). This one is mounted on an improvised anti-aircraft mount, but they’re normally seen as the secondary armament on BMPs and tanks, but have also been produced in infantry and AA-specific mounts.