A quick history of how the Partition came about is John Nosler was hunting moose in AK with his .300 H&H. He had bullets fail to penetrate at close range on a "mud encrusted" moose. He got the moose finally but he wanted a better bullet, and led to the developement of the Partition. The standard by which every other premium hunting bullet is judged by.
Federal just buys bulk Partitions from Nosler, as well as other premium bullet makers like Swift and Barnes. They load them up and sell them in their ammunition. Federal makes some of the best hunting ammunition this way.