My father recently inherited a Winchester Model 21 Side-by-Side Shotgun. It originally had a beaver tail forearm but my grandfather replaced it with a standard forearm because he thought it was more comfortable to grip. Somewhere along the line the beaver tail forearm was lost. I would like to find out where I can find an original beaver tail forearm for this gun. I'd like to get it as a gift for fathers day. Any advice would be greatly appreciated. Thank you.