To get Bol Skull you have to do the steps below.
1. Head to the planet Tatooine the
city of Mos Espa.
Once there head for the cords -2975, 2457.
2. Talk to Mat Rags, he will give you four missions and they also pay pretty good too, starting at 2000 credits. First you have to kill a Desert Squall, then a Greater Womp Rat, after that you have to kill a Matriarch Bantha and last a Grizzled Dewback.
3. After completing those missions he rewards you with 6000 credits and a Master Hunter Trophy.