The easiest way I found, you need 2 people, host a Player Match of Deathmatch on Jungle with a maximum number of players set to 2.
If your stood at the top of the steps looking down into the 'Jungle', if you follow the paths on your Right, you will come to a Courtyard-esque area, with a block in the middle. The Scoped Rifle can be found on the floor to your left as soon as you walk in.