Give one of these a try:
Big Bob Gibson's in Decatur. The original is located on Hwy 31. They have won several national competitions. www.bigbobgibsonbbq.com
Decatur is about 15 minutes from Hartselle to the North.
Johnnys BBQ in Cullman. Located on Hwy 278. Take I-65 south to exit 308 go east. One of my favorites. Take about 20 minutes from Hartselle .
If you are looking for a sandwich or chicken try Whitts BBQ in Hartselle.
Pigstand BBQ is located on Hwy 31 in Hartselle. It has recently changed owners. I have not tried it since the ownership change.