Hello, new to the site. The place you're talking about is Junior's Junkyard, owned by Junior Carpenter. He's been a friend of my family for years.
He's old as dirt now but in his younger years he did in fact chase trespassers from the property with a gun, under the assumption they were stealing auto parts, as most were. Nowadays I know the property is watched at night occasionally by some of his friends or employees.
During the day M-F? Just drive up, park in the small beat up parking lot out front, and walk in. Unless he's got something going on Junior usually doesn't mind people poking around as long as they're not stealing. (I have not seen him in a few years now so this may no longer be the case) Unless you've got a serious off road rig don't try to drive through, mud and rocks dominate the further you go in.
Worst comes to worst, bring him a 6 pack of Budweiser and he's your best friend.
Look for the old man with the crazy eye, that's Junior. Best of luck!