Yahoo, Gun shops Myrtle Beach. gives a list of three or four. I was visiting Myrtle Beach last month and went to two shops can not remember their names but if your like me you can not drive past with out stopping in. Good luck and have a good visit.
Hammer Down Gun Shop - on 501 across from Waccamaw Pottery/Hard Rock Park
Myrtle Beach Indoor Shooting Range-on 17 Bypass in Myrtle Beach
Coastal Sports and Range-in Murrells Inlet
707 Gun Shop- In Socastee on 707