Yep, you can purchase all the ammo you want in PA with no issues.
Now, Today, watching a FUDD's reaction to having to get a background check, requiring their Driver's License & Social Security Number to purchase one box of 3030 to sight in/Hunt with his old Winchester 94 was PRICELESS.😁
Same FUDD told me all us Semi Auto rifle owners are crazy for owning weapons of war, that the SAFE act was a good idea & the govt. would never try to confiscate our rifles!