.257 Roberts ammo is still fairly readily available. The .250 is not. Hornady ammo or brass only from Midway. No ammo at all from Graf's. Hornady brass only.
Anyway, knew a guy years ago who swore by a heavy barreled, 20", .257. Don't recall what rifle.
The important part is the length of the action. Your Mauser is a long action. The Roberts(2.223" case length) uses a long action. The Savage(1.912" case length) a short. Going with the Savage will require a spacer in the mag. Not really insurmountable, but the lack of ammo/brass will be.