The 300 Savage is an older round that is very similar to the 308. It will do almost anything the 308 will do. It came out sometime in the 1930's or so while the 308 came out around 1954 and about killed off the Savage mainly due to it beingwidely used in the military.The 300 Mag is a magnum, sort of a hot 3006 with a belted case and a longer case to hold more powder. They are all 30 caliber. Thats it in a nutshell without going into great detail.