 The rifle can vary from the very basic break-barrel spring-powered rifle to the most advanced electronic recoil-less pre-charged pneumatic (PCP) rifle.The most popular calibre for HFT is 4.5 mm (.177 inches) because of its flat trajectory, and telescopic sights capable of 10× magnification are favored.The maximum output power of the rifle must be limited to 16.3 joule.