If this is a first person weapon model you're going to want to have a lot more polygons at the top back of the receiver which will be right in the player's face.
"it should select both polygons, edges and vertices in one mode." Orionflame 3 has this feature, called intelliswitch. Demo here: http://maxima.orionflame.com/
1000+ hours of code? Impressive! But that's no match for the 32,382 vertices I have, or even my hidden cache of 1.75 million bytes of polygons! Touche!