Off-Centre Gas Port Hole in INSAS: A Critical Design Flaw or Tolerance Artifact? In normal AK style gas-piston system, the gas block’s port is aligned with the centre of the piston, and op-rod axis. If the port is not centred, several things can happen, depending on how far off it is. What happens if the port is off-center ? ·      Side loading and cocking of the piston: If the gas hits the piston off-centre, the piston tends to tilt sideways inside the gas tube bore / gas block bore. This increases friction and leads to uneven wear on one side of the piston and the gas-tube inner surface. Over time this can cause scoring, galling, or even binding, especially if clearances are tight or the tube is worn. Reduced reliability and increased bolt-carrier velocity variation: An off-centre blast can make the piston start moving slightly at an angle, which may reduce the effective push on the bolt carrier and increase the likelihood of short-stroking or excessive ...