History of the 338 Federal Cartridge
The 338 Federal cartridge was announced December 2, 2005 by Federal.
This cartridge has existed for years among the wildcat community, known as the 338-08, the 338/308, or the 33-08. As such, there should be load data floating around for it, but it is hard to know what pressures these are loaded to.
According to Federal, ammunition will be available Spring 2006. Dies will be available from RCBS (I already have a set). Federal does not publish load data and will not do so for the 338 Federal cartridge. SAAMI approved the cartridge specification, apparently around June of 2006. Federal does not sell brass for any cartridge and will not do so for the 338 Federal.