I used a rubber washer from a sink washer kit. I trimmed it a bit and what I like about the rubber is that when you tighten it up the forend stays put, without it being super tightened. It is important to make sure the forend does not touch the barrel on either side also. I shot this rifle yesterday at the range and once again it shot 3 3shot groups at very close to an inch. The load being 57.0 grs. of AA4350 under a 165 gr. Remington PSPCL. Function is perfect.