For Marcus Zavala, cleaning guns is a Zen-like process. “Each one is like its own little project,” said the 28-year-old Texas native who is working on his doctorate of pharmacy at the University of New England while working at The Gun Cleaners in South Portland. “They require different things.”

Working with a handgun on his hip and a big brimmed cowboy hat perched on his head, Zavala meticulously dissects an AR-15 rifle until each part is separated out on a bright yellow work rag.

He then dunks the parts in a tank of heated solvent for a minute and a half. The tank is pulsated with ultrasonic waves, which help break up carbon and other particles. After a quick rinse the parts are dried, submerged in another ultrasonic tank – this one filled with gun lube – and reassembled, ready for the customer.

“I feel like I’m doing the community a service,” said Zavala, who learned how to clean and disassemble a gun from a young age. “I’m sending people who do carry out into the world with clean guns that will fire correctly.”