L.G.,
A "barrel block" holds the complete barrel and action in the stock. It clamps on the barrel just forward of the receiver and is usually glued or bolted into the stock. Nothing touches the stock except the lower part of the block. It is a particularly useful means of attaching to the stock when you have a very heavy barrel which may be causing the receiver to bend due to barrel weight. To avoid this problem with heavy barrels, you can alsao bed the first 4 to 6 inches of the barrel to take weight off the receiver. Hope this helps.
Richard