Magic Stone Spell - Throw 3 Rocks at Once?

[Slamron]

I have a player that likes to use this spell, and I am trying to find clarification on it's use.

Magic Stone:

You transmute as many as three pebbles, which can be no larger than sling bullets, so that they strike with great force when thrown or slung. If hurled, they have a range increment of 20 feet. If slung, treat them as sling bullets (range increment 50 feet). The spell gives them a +1 enhancement bonus on attack and damage rolls. The user of the stones makes a normal ranged attack. Each stone that hits deals 1d6+1 points of damage (including the spell's enhancement bonus), or 2d6+2 points against undead.

So, my question:

1. Can you throw or sling all 3 pebbles at once? If so, 1 attack roll, or 3 separate? Up to now, I've allowed my player to throw 3 at once, since I can easily see holding 3 pebbles in one hand and throwing them. I said that using a sling, however, he could only fire 1 at a time, since the basket on the sling would be made for only 1 sling bullet.

Thanks

[LazarX]

One rock per throw just as if you were throwing a standard rock big enough to do real damage at range.

[Kazumetsa Raijin]

1. You can throw or sling only one at a time.
2. 1 attack roll, 1 pebble.

This spell simply lets you Transmute up to 3 at one time, for the purpose of later throwing/slinging them. If you happen to have multiple attacks with a full-attack, you can throw one after another.

[Slamron]

Thanks for the answers. I have other concerns with this spell.

Would the player's strength bonus get added to damage? I believe it does since STR bonus is added to sling and thrown weapons. If that's true, then real world physics would be involved somehow. Therefore, shouldn't the slung magic stone do more damage than a thrown magic stone? By the rules, I don't think throwing a sling bullet would do any damage, but slinging one of course does 1d4 + STR bonus (for a medium creature).

[Lakesidefantasy]

The strength bonus to damage applies in both cases.

I suppose the benfit from throwing the stones versus slinging them is the incresed range increment, 10 ft. vs. 50 ft.