Lets see: we pour the stone, the stone expands, the analog is a piece of machined metal with external retentions. Here you go.
Hard to believe? You can check it yourself. Take a stone model with analog. Glue the stone model to a cardboard. Grip the analog with an instrument such as "mosquito". Take a pen or a pencil and draw a line adjacent to the handle of the "mosquito". Then rotate the "mosquito" and draw a second line. Now you see? Yes you do. Want to solve that problem? Start taking impressions with G-Cuff. With G-Cuff you don't need analog.