I like the concept, but I'm not too convinced on the output. Sure, overall it's quite nice.
But an actual cannon would be big, where as this is really small. I guess the user can draw the idea of strength and durability from this image, but not too sure its portraying the idea of thinness too well being a cannon, as I see a cannon as a big and thick thing in my head.
Still, nice idea! Perhaps if you develop the idea more you could consider the size thing different.