It could also be a 300 savage could it not. My 99 is in 300 sav and it has a pretty close serial number. If you don't want to take it to a gunsmith you can always do a chamber cast. I am a gunsmith and I use cerosafe for casting chambers. Its pretty easy and most of the places that sell it will tell you the cartridge if you send in the casting. I usually use midway usa or http://www.buffaloarms.com