Mentos and Coke

I'm not sure what purpose shooting the bottle served, because it seems to me that the bottle would have exploded anyway from the pressure; but I could be wrong.
That's a cool little rifle anyway, so I'm not complaining.
Using the magnet was an ingenious idea. I'll have to try that, to see if it builds enough pressure to make the bottle explode. I saw the Mento & Coke geyser trick on Mythbusters and it looked pretty impressive, but I guess that doesn't necessarily mean it builds up enough pressure to blow up if it's enclosed.