The FAMAS is the first unlockable assault rifle for the assault class. You can get it by completing the assignment "Best Friends Forever." Once you've done that you have the FAMAS.
Level 40
Unlock it by playing as a support.
the famas is a gun from the map pack "back to Karkand" and they have multiple new guns that you recieve by completing assignments.
you can get it at campaign or unlock it on multiplayer
Battlefield 3 does have Co-op mode, you can also unlock weapons for use in Multiplayer from playing Co-op.
In Battlefield 3 online multiplayer, the player can unlock weapons and other gadets by gaining points. The "C-4 Explosives" unlock for the Support class is unlocked by gaining 4000 score as the Support class.
The Battlefield 3 Limited Edition includes the standard game, but will automatically unlock the 'Return to Karkand' expansion when it launches in December.
Trust me, you'll get so bored with having nothing to unlock. Just save your money and unlock the stuff
The last unlock for every class is the other teams weapon for that class.
You can pick them up from dead soldiers on the battlefield, but other than that, No. Well, not legaly anyway.
You unlock the l96 by completing the recon assignments in the back to Karkand expansion pack