Prepare grill to medium-high heat.
Combine jelly and water; set aside.
Combine paprika and next 6 ingredients (through pepper); rub evenly over pork. Place pork on grill rack coated with cooking spray; cover and grill 15 minutes, turning pork occasionally. Brush pork with jelly mixture. Grill an additional 5 minutes or until thermometer registers 155° (slightly pink).
Place pork on a cutting surface. Lightly cover with foil; let stand 10 minutes. Thinly slice pork. Combine ranch dressing and barbecue sauce. Serve pork and ranch mixture with buns.