Step one, find a rifle and an axe.
Step two, find a second axe or second rifle.
Take second weapon 'to hands' and ensure there is not enough space in your back to store chosen item. (This is important for the sawed off as it can fit into the backpack).
Log off of the server.
Log back into the server. Your 'extra' weapon will be in your inventory, and there will be a duplicate of it on the ground in front of you. Works -every- time.