This might actually be of interest to some of you that have wanted the Knoxx SpecOp stock for the 870 20 ga, but since Knoxx stopped making them you were out of luck.
Here's an adapter:
http://mesatactical.com/products/lucy-12ga-to-20ga-stock-adapter/
Nice. I wish I would have seen this a couple months ago. I put an ATI on this 20ga.