You can find the RPG in four places in GTA V. Or you can just use a cheat when you’ve acquired one to top up your ammo to the maximum 20 allowed at any time. At all of the locations, the RPG will re-spawn after around a minute.

Watch the video to see all four locations as below:

  1. On top of the suspension bridge. You’ll either have to do the long climb to the top or land a helicopter.
  2. At the cult’s fort. You’ll need to shoot your way past the inhabitants first, but when you have you’ll find it in the church’s side building on the far right of the fort.
  3. On top of the NOOSE building. You can either climb up the ladder or land a helicopter on top.
  4. This one is by far the hardest. You’ll need to find the scuba dingy on the south of the map or at the pier where you do the Abigail freak mission. Then you’ll need to drive it to the big lake and dive down to find the crashed plane. The RPG is inside the fuselage of the plane. While you’re down there, you’ll find lots more weapons to top up with.
  5. If you’ve already acquired a RPG and can’t be bothered to wait for the ammo to re-spawn, then just use the 1-999-TOOLUP cheat to bag 5 ammo, plus top up the ammo on all the other weapons you hold.