According to Gunfire, the polymer Specna Arms J-Series CORE series is a pricebreaker. Leszek explains more in this video... "Specna Arms J-Series ™ CORE ™ carbine replicas are made primarily out of durable polymer reinforced with nylon fiber, making the replica lightweight and comfortable to use. Pistol grip, receiver, handguard with the gas tube cover, gas tube and the front sight post are made of polymer. The gearbox has 8 mm slide bearings and steel gears fitted on them. The system is secured by means of four anti-reversal latches. A light, made out of polycarbonate plastic piston is fitted with a full steel tappet plate increasing its durability. A type 0 cylinder and a steel circuit-breaker are also used here. The durability of the components allows for using M140 springs."