In MW3 you level up your gun by using it. You get xp by getting kills or destroying enemy equipment like a helicopter. If you use it enough you will unlock new attachments camouflages and other things.
What you have to do is level up till you can buy it or find cheats online but i have already cheacked for you could not find any :/
No, you need to rank up your gun level again.
you level up to level 80
The best mw3 gun is the L118A but that's because I like sniping.Or if you put the first one on perk 2 its the best quickscoping gun
Level 80.... 20 prestiges
The clan is rhvg
Yes, you can i did it in the last level of mw3
You unlock Claymore at Level 53 in MW3! :-)
Level 69
RSASS sniper rifle
Either an M4A1 or M16
Level 80.