Please see #5 at 
http://www.vikingsword.com/vb/showth...t=camel+cannon
Could this also be a camel gun? A lot of indication of something Indian going on here ...My camel gun is very similar. Take all the woodwork to one side and the barrel could easily be from a camel gun...  
Here is a camel gun below usually fired from a crouched position or dismounted.