There are several different alloys in the "Cerro" family. In one machine shop, I worked in we used a lot of "Cerro-Bend". I am not certain just how it compares to Cerro-Safe but was very similar. Lead alloys will have different shrink rates according to their alloy. Bullets cast from the same mold of Wheel Weights & Linotype will not end up the same size. Add to that particularly with older rifles & handguns there can be a good bit of difference in actual bore sizes. Mold makers to keep down their inventory generally try to make their molds large enough to fit the max they see as being needed & depend on sizing down for the variables.
