Ok so this is what I did:

1. Fast travel to boulder city

2. If you have Boone, tell him to wait cause you are gonna be killing some NCR dudes

3. travel toward Hoover Dam and you will see a camp to your right by a broken building

4. Go on the hill behind it and just start whipping grenades

5. If you are lucky, 2 NCR rangers will come up and try to kill you

6. Kill them and take their stuff

7. Go back to Boone, and now you and boone have the sik NCR ranger gear like on the cover and you get an anti-material sniper rifle