First off, Make sure to always rest the gun close to the hinge. Make sure the action is closing tight. Try changing the tension on the forearm screw. Some guys slip a rubber O ring over the forend screw to dampen the vibration of the forend. Always pull the trigger the same way every time. They have a transfer bar. If you shoot reloads, be sure that they are not to long. The handi has a short chamber and throat.

For more info check the NEF centerfire site at www.graybeardoutdoors.com.