Go to the Item Shop
On the initial screen (All Weapons), you will see the Katana and the new weapon, M16A3 LMG.
Click on the katana, your character should now be stashing with it.
Now click on the M16A3 LMG before the first slash is completed (if you were too late, click the Katana again)
Voila, your new melee weapon, the M16A3...
Just a funny bug... nothing much.
(Its funny that they stash with the gun).
Last edited by smart_brian; 12-15-2011 at 02:33 PM.