Here are codes for 4 of the "Find all Five" unlockable weapons in Battlefield Bad Company
M60 machine gun
try4ndrunf0rcov3r
QBU88 sniper rifle
your3mynextt4rget
USAS12 shotgun
aw3somef1rep0wer
Uzi
cov3r1ngthecorn3r
Go to the unlockables menu and press "start" to enter the codes.