I knew Savage went to birch stocks late in the production runs, but I didn't know they put birch stocks on while they were still making the rotary magazine models.
It's true that the rotary magazine -- one of the niftiest magazines ever designed, IMO -- got to be just too darned expensive to manufacture.
I think the Savage 99 is the best lever action ever made, bar none. Wish I could afford to buy a good example in .243 and .358; there weren't all that many made, and finding one out here on the left coast is difficult, and if you do, be ready to dig deep into your wallet.
About the .300 Savage round: I recall reading a piece by Jeff Cooper 50 years or so ago in which he said that when the Army Ordnance people were casting around for a replacement round for the venerable '06, one of the rounds tested was the .300 Sav. They even modified machine guns to see how it worked.
It didn't, very well. Apparently the short neck and steep shoulder (at least, in Cooper's opinion) caused serious feeding problems in full-auto fire mode. So the 7.62/.308 was the eventual solution.
But the .300 Sav still is a very fine deer and elk round out to around 250 yards. Been a long time since I tried to hit anything at any longer ranges than that.
My older son, now 38, surprised all his blastfire magnum buddies by showing up for a Texas hunt with his grandfather's 99 in .300 Sav. Outcome: one shot, one dandy 5-point buck.
Bill