Greetings: I bought a new stock that has a groove cut in the bottom of the forearm. I assume this is where one would install some type of metal rail to hold accessories like bipods, had stops, etc. I see a lot of stuff on the web for AR platforms, but nothing for a traditional target stock. I see pictures of them, but have not found a proper description, or a supplier. I found something called an "elevated" picatinny rail. Has about 3/8" of height to it. Not sure if that would work. That was from Yankee Hill Machine Co. What are these rails called and where can you buy them. Please advise.