As a player I always found that you could carry whatever you liked within reason, but still prefered to maintain my original issue weapon(s) out of a sense of personal pride and satisfaction, and also in order to maintain compatibility of ammunition type(s) with my team mates, so as to increase our overall battlefield effectiveness as a team.
So what was Wolfgang Heckler's issue weapon again? An EZ-curl bar and disc weights?
__________________ "It is better to be feared than loved" - Nicolo Machiavelli