ROCK HILL • Sitting inside a Starbucks, sipping black coffee, joking with the baristas, Dan Zimmerman doesn’t look like a gun guy. He looks like a guy who might work in accounts receivable, which is what this Olivette resident did for years. He is 53, balding, wearing tortoise shell glasses, carrying a little extra weight and dressed in the beige tones of business casual. He smiles easily. He is working on a laptop at a back table. He also might be packing heat. Could be his .38 snubby. Maybe his Kahr 9 mm. He won’t say. “I really don’t talk...