@pedro: you definitely need to merge your vertices. as i can see from the model's in-engine shading, all faces aren't connected which produces the flat-shading look. this is a known problem for importing files, esp. 3ds and obj files, int MED. How to sove:
1)import your model in MED
2)go to vertices selection mode
3)tools>mesh tester (may take a lil while)
4)you get a message box about "closed"(good) and "open"(bad) meshes.
5)klick OK and now "merge" (toolbar>right)

ps: very nice model., congrats. the ammo skins are beautiful as well. impressive!