Its a Mauser 98 Paterned Mountain Carbine. But I have read that its a Small Ring, with Metal removed to lighten it.
You can Use commercial loaded cartridges just fine.
Remington, Federal, and Winchester all offer cartridges, that are slightly down loaded, and perfectly safe. I would stay with the low velocity cartridges if it were me, because when you remove metal, you weaken it. So be safe.