Today I tested my 'shooting' code for your problem (because I remembered something...) The gun didnt hit the edges of the models , because their bounding box doesnt reach that far. I think you're experiencing the same problem here. (BTW , result = 0 means it didnt hit anything) If you try with a .hmp file I'm shure it'll work , because terrains are handled differently from models altough there are a few other problems when using terrains (models falling between two polygons). I even set my.polygon to my model (when I tested) and it didnt worked again , so the solution is to use .hmp terrain or to move the houses with collision detection.
(because I remembered something...) The gun didnt hit the edges of the models , because their bounding box doesnt reach that far. I think you're experiencing the same problem here. (BTW , result = 0 means it didnt hit anything) If you try with a .hmp file I'm shure it'll work , because terrains are handled differently from models 
