2 players stand in a close proximity to one another with no weapon in hand or on their back. The weapon to be duped is placed on the ground where both players are able to access it in the vicinity. an apple is also placed on the ground in the same vicinity. One player eats the apple from the ground and as the eating animation begins, both players drag the weapon from the ground to their "hand" slot at the same time. The player who doesn't eat has the weapon appear in their hands immediately. As the player who ate the apple finishes the animation, the weapon will then appear in their hands also. At this point, The player who ate the apple then presses the "X" within the "hands" slot which causes the weapon to appear on the back of the other player as well as in his hands. From here, the player with 2 weapons simply logs out and back into the same server and upon returning, both weapons are available to be used.

Here is a youtube link to a video tutorial of the above mentioned issue. (note: this is NOT my video nor am I affiliated with the individual who made this video)

https://www.youtube.com/watch?v=TM6aXJecTjc

This weapon dupe, upon discovery, was tried by myself and a friend with a number of different rifles to see if their were any limitations or exclusions. After trying 5 different rifles (sporter, blaze, winchester, SKS, AKM) there was no issue with any of these and all weapons were able to be duplicated. A secondary discovery that was not tested in depth was that when enacting this method, it would seem to force a server restart. I was not keeping a tally but I am fairly certain this was the result 100% of the time after the first full cycle of the above outlined duplication method.