Map: Discarded
Mode: Conquest (Solo/coop)
Bot Difficulty: Easy
Specialist: Boris
When the game loads to the spawn screen, select Boris as your specialist and then select the vehicle spawn option under your team's main spawn point. Select a helicopter to spawn in and wait for the countdown to end.
As soon as you have control of your helicopter, fly straight to the ship in the middle of the map. There are two capture points on top of the ship (north and south). Fly to one of these points, leave your helicopter and fully capture the point.
Once the point is captured, you want to place your sentry gun on the edge of the ship facing the enemy team's main spawn point (look at your mini-map and make sure the sentry gun is within the grey square around the capture point). The sentry gun will angle down and target enemies as they get close to the ship.
Here's a link to a screenshot I took (sorry I'm not sure how to embed images into guides). Notice how the sentry gun is right at the edge of the ship and is within the grey square on the mini-map:
https://www.mediafire.com/view/3c23z04rzu4obkf/33ecd834-a9c0...Bots will eventually destroy your sentry gun, so be prepared to replace it. Additionally, there may be times where there aren't many bots on one side of the ship. In this case, you can either run along the opposite ledge of the ship and place your sentry gun or run to the opposite capture point on the ship and do the same (assuming your team holds it). Just remember to place the sentry gun within the grey square on your mini-map!
Note: Bots will occasionally storm the top of the ship and attempt to take both control points. Watch your mini-map and listen for the sounds of bots running upstairs to the top of the ship.Note 2: You can use the achievement tracker function to track sentry gun damage during the match. I managed to get 2500 damage before the match was halfway over using this method.