Partly, but the frame had a lot to do with the level of the playing surface as well. Before you can level any table, you have to know what the frame conditions are. An example of what I mean is think about this for a minute. If a GC frame is higher on the outside edges where the slates sit, and you screw them down to the frame, the slate is sitting on the outside of the frame, the slate screws are pulling the slate down inside of that area, so it bends the slate down in the middle. But if the inside of the frame is higher than the outside, then screwing the slate down to the frame bends the slate over the inside of the frame causing the slate to crown.Is that because the GC1s used Brunstone
You have to know the conditions of the frame first, instead of just assuming the slates are crowned or swayback in the middle.
Put a straight edge across the frame, look at how the slate is going to be sitting on it before you throw the slate on the frame and screw it down.