Quick Load is one that is often used. Marty of Teppo Jutsu has developed quite a few wildcats and one of his most successful is the .458 SOCOM. While it is no longer a wildcat, load data is still pretty scarce and none of the reloading manuals I know of offer any data. All the data we have on it comes from the initial loads that were done with Quick Load and from people actually loading for the round. It is not perfect, none are, but Quick Load does give you a very good place to start. Marty has used QL to help me develop loads for my .358 HDH as well as the 470 Rhino, .500 Phantom, and .338 Spectre.