Ah. The question. He doesn't have a good enough read here yet to know what kind of response the truth will get, so he decides to take the safer route of being vague but technically truthful. He's never been good at lying but he's fantastic at delicately sidestepping around the full truth in a way that sounds reasonable enough.

"You won't accidentally set it off, trust me. But it's not dangerous. It, uh. It's for calming myself down. It keeps my thoughts in order."

As far as he's concerned that's all true.

"I know that's not generally how a gun works but it was the first thing I could think to build, so." He shrugs as he approaches the rocks. He hopes it didn't wash up here... what if the bulb broke? What if something bent? He can probably fix it but it's going to be such a setback...