I think that works pretty well. We can just modify numbers...
Spit Stones (Ex): An elephant swallows large rocks and stores them in its gullet, which superheats them magically. An elephant bird can spew these rocks with tremendous force at opponents up to 50 feet away as a standard action, doing 1d10 plus 1d4 fire damage. This is a ranged attack with no range increment. An elephant bird’s gullet may hold up to 3 stones, which are launched one at a time. An elephant bird that runs out of stones during combat continues the battle fighting with beak and claws. An elephant bird may snatch and swallow a rock as a full-round action to replenish one stone, but does not usually stop to do this during combat.
All numbers negotiable.