What engineering decipline does weapon design come under?
hga: I would go for Mechanical Engineering if I were you.Do you live in or plan to study in the US?  Even if you don't, try contacting the National Shooting Sports Foundation (NSSF, http://en.wikipedia.org/wiki/National_Shooting_Sports_Founda...) and Sporting Arms and Ammunition Manufacturers' Institute (SAAMI, http://en.wikipedia.org/wiki/Sporting_Arms_and_Ammunition_Ma...).  In Europe, the equivalent of SAAMI is The Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives (C.I.P., http://en.wikipedia.org/wiki/Commission_Internationale_Perma...)I can dig up a German small arms research organization out of my email archives if you're interested.