Dude, listen to the advice.
There's nothing technically WRONG with the FAMAS. I myself had a nicely converted one with a 590mm PSG-1 tightbore and a bull barrel outer and the thing absolutely rocked ass. FAMAS G2 Sniper goodness. I actually have a video of it in action here:
YouTube- Killing Spree 3
But I had a lot of help and support for putting that package together and from experience...I do not recommend it for new players. Get something more generic like an M4 which you CAN mess around with and figure out the customization you want to go for.