@ Nemo: I use to have a Model 99 in .303 Sav. 1917 manufacture. As you mentioned, ammo is a bitch to find however, you can roll your own.
I bought a
.303 Sav. die. Took 30/30 brass and re sized them in the .303 die. You will need to trim the resized case a hair. I forget how much though. You will have to look that up.
WARNING WILL ROBINSON...If you do roll your own use less powder than what is recommended for a factory load. I use to load it with IMR-3031 powder which I can not find anywhere anymore. It's all mute as I sold the rifle in my late teens to help pay for the next semester at college.
On another note: There are few model 99's that do not have a crack in the stock just past the receiver at the grip. Also switching out the stock is great, so the rifle becomes a shooter HOWEVER do not throw out the original stock as then the rifle is worthle$$. The stock and fore grip must have the same serial number as the receiver's to be worth anything.
That was a fun rifle.