i followed the following steps on my xbox with no return it did not work
1. Create a class with 1)M4 Carbine w/Red Dot...2)AK-47 w/Silencer....3)Perk 2 is overkill...... All the other stuff doesn't matter
2. Create another class with 1) M4 Carbine w/Silencer..... 2)AK-47 w/ Red Dot....3) Perk 2 is overkill...... Once again all the other stuff does not matter
3. Get into a match
4. While the countdown to the beginning of the game is going on.... continuously switch from Class #1 to Class #2.
5. Once the game has begun, eject your game once and put it back in.
6. You now have a M4 Carbine w/ Red Dot and Silencer.
NOTES: This was tested on the PS3. It is unknown if this works on the XBOX 360. For Step #4 to work correctly, your connection must be good. Basically you must have at least 9 seconds to continuously switch back and forth from Class #1 to Class #2. Only your M4 Carbine will have a Red Dot and Silencer. Your AK-47 will not. This procedure only works for the M4, though the second gun (AK-47 in these steps) or interchangeable. This does not work for ACOG and Silencer, only Red Dot and Silencer.
This Tutorial Is From crapper16 -- at DONT ADVERTISE!