Java volcano in Indonesia akin to potato gun

Kazlor writes: Just saw this earlier on BBC earlier. http://news.bbc.co.uk/2/hi/asia-pacific/6392995.st m Apparently they're trying to plug up the volcano, Java, in Indonesia with cement balls, weighing up to 250kg (500 pounds). Common sense from playing with tennis ball cannons and potato guns as a kid tells me that it's gonna use a side pocket to relieve back pressure before chucking it out like someone drinking water down in Mexico.