Have a rifle on your back & the rifle you wish to dupe in your hands.
When you go to log off you character places the 2nd rifle (one in hand) on the ground at its feet as it sits for the 10-15 second log off timer.
Another player can pick up this gun thus Duping it.
When you log back into another server you still have the gun & so does the other player.
We have tested this a few times Fri/Sat this week. Mosin, SKS & M4.
Gun, Attachments, Ammo & Clips all dupeable.