What Mike said
I cannot urge you strongly enough, follow his advice. DO NOT TAKE APART THE MAGAZINE! In fact, do not disassemble the action at all if you can help it.
I inherited a Model 99 in .300 Savage from my father. Older gun, brass cartridge counter, 24" bbl, safety on the lever, schnabel forend, checkered stock. The safety was on when I got the gun, and took some soaking in WD-40 and a couple of judicious "raps" to get it to move. The action was all gummed up from the dried oil, as the gun had not been used in many years.
I was going to take it all apart and clean it up, but I was smart enough (got lucky) and found the instructions before I started. NRA's book Firearms Disassembly (vol 2 IIRC), and justr looking at the instructions (and WARNINGS) about the magazine convinced me it was nothing I wanted any part of. I did clean it using WD-40, and then other spray cleaners, and today the rifles cycles and shoots quite well. One word of advice, .300 Savage ammo is not a very commonly stocked caliber in the west. You may have to go to a few places before you find it on the shelf. You may get lucky and find someplace right away, or you may have to look around a bit.
It is a bit more popular in the east (where I grew up).
You can, of course order it, it is still in production. Remington loads the 150gr and 180gr bullets. It may cost a bit more than more popular calibers, but not a lot.