In a medium bowl, melt butter in microwave. Add garlic, mango chipotle rub and salt. Mix well to combine.
In a gallon sized freezer bag, add shrimp and marinade. Seal bag and cover shrimp with marinade. Let marinade for 3-4 hours.
Preheat pellet grill or other grill to 375 °F.
Skewer shrimp on kabab skewers and cook until slightly pink.