Explosive.

This is coolbert:

From the latest edition of the DEBKAfile newsletter some further clarification regarding the use of the .22 caliber Ruger rifle as an anti-riot weapon:

"Israel security forces may use live fire for Palestinian rocks, firebombs, and 'popular terror'"

20 September.

"Israeli security forces now authorized to use Ruger rifles in life-threatening situations generated by Palestinian terrorist attacks with stones, fire bombs or mob riots. This weapon fires light 0.22 (5.59mm) bullets packed with a small amount of explosive which can cause injury within a 100m radius. The new rules of engagement are effective in all parts of Israel, not just Jerusalem, in view of extremist Islamist unrest in Israeli Arab districts."

The use of ammunition smaller than a certain caliber AND CONTAINING EXPLOSIVE MATERIAL FORBIDDEN BY THE ST. PETERSBURG CONVENTION OF 1868!

And from a source knowledgeable in JAG the use of such explosive weaponry not so totally illegal as I might have thought:

"Those rules apply in the event of war. Unless someone declares Palestine to be a state, the rock throwers to be soldiers, and a state of declared war under way, nothing legal or illegal is in effect here."  

"The only laws applying would be the laws of the nation-state where things are happening--as in Israel . . . But there are no violations of any actual international laws."

coolbert.