Grooves in AKM Piston head, Are they Functional or Aesthetic Most of the people think the grooves is just for Aesthetic or for reduction of weight, but it is the most important feature for cycling and reliability in the AKM. In simple terms the grooves in the AKM gas piston head act as a labyrinth seal and a carbon scraper to maximize gas pressure and prevent fouling. Unlike automotive engines, the AKM piston head does not use flexible piston rings to seal the gas from escaping through the loose tolerance of the design. Instead, Mikhail Kalashnikov designed the solid steel head with specific grooves to keep the rifle reliable under brutal conditions. 1.     The Labyrinth Seal Effect: When high pressure gas expands from the barrel into the gas block, it meets the face of the piston. As gas tries to escape through the tiny clearance gap between the piston head and the gas tube wall, it encounters the sharp edges of the grooves. ·     Creating ...