Kill a target from 70m or more with the bow (Single Player only).
Again, you'll need to head to any store and grab the Recurve Bow from under the Specials menu which you can buy or get for free by unlocking Radio Towers. Next, make sure you buy the Marksman Sight for $300 as this will help. Now head to any un-liberated Outpost on the island and try and get to a good vantage point where you can look over it and see the enemies inside. Tag the Outpost with a custom marker from the menu and walk back to the vantage point until the distance meter in the corner shows 70m+.
Now located the easiest target and aim true. Use the new sight to help you gauge the distance and see if you're landing too short or shooting too far. The Bow is a one hit kill, so all you need to do it get that one hit.
First of all you will need to get the Recurve Bow from a weapon locker or general store. You can either buy it or activate radio towers to get it for free. Also buy and equip the Markman Sight. It's a very useful attachment for long range shots. Now search for some enemies and put a marker on their location on the world map. Walk away until the marker shows a distance of 70+ meters and take the shot while the enemy is standing still. The Welshore Wrecker's House Outpost (coordinates X: 437.9, Y: 795.0) is near the starting area of the game and one of the best locations to get this done early.
Easiest way to do it is look at the distance bar on the Bow sight. Go to an outpost with snipers and get as far away as possible an snipe one of the snipers with the bow. Snipers are easy because they just stand in one spot.
got it... if anyone else is in this situation go to the mountain located at X:355.9, Y:698.8. even if u have done all outposts, missions, and even cleared this place before they respawn. Sometimes, however rakyat warriors are there instead... fast travel somewhere and come back and eventually you will get pirates... having high ground doing this makes your bow adjustments not as crucial.. njoy :)
I was having some problems with this too. I kept getting enemies from further than 70m. on a whim I made an exploding arrow, got on high ground and hit an enemy. then the great sound of the achievement popping came about.