I am a huge fan of the Mythbusters and when i saw the episode with shooting grass "needles" through a palm tree i think something might could have changed the result.

U could get a piano wire through the tree but none of the others. mebe because of lack of stiffness or mebe because when you used the grass straws u fitted like the whole tube with "bullets". making the surface of the tree crumble together and making it more harder to penetrate.

when you used the piano wire that is more stiff/hard, it went straight through.

could it be that if you used a single grass straw that the result might change ?

sorry bout my english .. im a danish fan of the show.

regards
Thomas