Being how popular they are in 12ga I'm not sure why Mossberg and the aftermarket doesn't offer a corncob forearm for a 20ga Mossberg 500. I've been checking up ever month this year with Mossberg parts department for a corncob forearm from a 20ga 590 Shockwave but they still are not offering them. I finally found some on ebay. They were new parts so I'm thinking either they were parting out Shockwaves or selling leftovers from aftermarket add-ons. I paid way too much for it but I had to have it. I removed the hand strap. Can't wait to see how it performs on this year's dove season.