Barrow said he was startled the first time the box was triggered on Dec. 11.
"I didn't know what was going on for a minute," he told the Tacoma News Tribune. "I thought it was somebody being shot because I heard her scream, so I grabbed my Mace and went outside."
Surveillance footage Barrow posted to YouTube shows a woman attempt to take the package from his porch, but scream and run off empty-handed when the blank round is triggered.
"I know it's crude, but there's nothing scarier than a 12 gauge," Barrow said.
Barrow said a second incident a couple days later left the attempted porch pirate so startled that he dropped his cellphone while fleeing.
"Poetic justice," he said.
Barrow said he conducted numerous tests on the box to make sure it couldn't injure would-be package thieves. He said he even tested out the box with a tomato inside to make sure it wouldn't be harmed.
Tacoma police spokeswoman Loretta Cool said investigators do not recommend emulating Barrow's idea.
"If the would-be package thief is hurt in any way, the homeowner would be responsible," Cool said.
She said the box might actually be a violation of current laws, but it would be up to prosecutors to determine.
"I believe there are criminal charges, but it would be up to them if they charged or not," Cool said.
