ORIGINAL: chiefks
If the whitetail buck skull shrinks, that will affect the antler spread. You can prop the antlers open and maintain the current spread though. Never tried it, but I've been told that.
Technically, for official scoring, it is not legal to artifically interfere with the drying process. To block the spread of a buck means you risk splitting the skull plate of the buck. If that happens it will not be scored. The skull must be intact. The deer I have scored avg about 1/4" shrinkage in spread. All I do is let them dry standing the racks on their tines, upside down.