Tutorial: 1. Prime SLE (system-link exploit) 2. Create an xbox live private lobby 3. Go to custom classes, chose any class, and then choose a gun that has the proficiency you want on another gun. Go to the proficiency interface of that particular gun, and stay there. 4. Sign-in with your second account (offline account) 5. Go to the exact same class that you chose and the exact same gun slot. Choose a different weapon that you want, this weapon will be the weapon you are going to add the proficiency to, and then press back until you are at the system-link main interface. Press back once more and you will be at the proficiency interface of the first gun. Chose a proficiency and you are done
this is one i fount quality is crap and he does it a little different you dont after search for a match! just go to private