They both make sense to me. I was born over off Liberty Road in the Lochearn area before moving to West Friendship. My Uncle (his hunting partner) was off Sudbrook Lane which was near Mountainside. I would imagine he bought that ammo back before 1972.
Mountainside was farther west. They were in the shopping center at Deer Park Rd, near the RV place. Clark, the owner was a great guy. Think of a milder version of Lou. They were the place for reloading supplies in the area. Always fully stocked.It was a great shop to go to. I used to trek out there from Towson.
Whoever said you needed to know they were there was correct. As I said, they were in that mall (Deer Park Center??) and only had a tiny sign out front.
The funning part was the shop was inside a mall, right next to a day care. I have a couple of display signs from the shop I got from them when Clark retired and closed up.