Airrow is how it is spelled if you want to do a more in depth
search, and yes I am familiar with them.
They are interesting modern renditions of an old idea.
There are many old harpoon guns that functioned in a similar manner.
Watch "Jaws", the old Shark hunter has a Martini version.
There are some rifle grenades that function in a similar manner also.
a neat idea, but A crossbow would be more practical I believe.
http://www.swivelmachine.com/html/rimfire.htm