I have never heard of the “Gepard GM6 .50 Caliber Heavy Sniper Rifle” before.
From the manufacturer’s website:
The Gepard GM6 ‘Lynx’ is a semi-automatic anti- material rifle. Thanks to the unique barrel recoil technology (SERO developed), the rifle’s recoil is less than the other rifles’ in the same category, and it makes its portable size only 915 mm. It operates with standard 12.7×107 Russian or standard .50 Browning rounds, and its penetration capacity is not less than the other destroyer rifles’ with longer barrel.
Its Purpose to stop or disable targets such as light armoured vehicles, armoured rifle troops, light shelters and buildings, radio- electronical constructions, missile launchers and hovering helicopters from 600-800 m range.
Check out the video, and notice how much the barrel recoils: