Plastic solution blocks guns from firing.

• Author: Beidel, Eric
• Position: TECHWIRE

Sometimes the best remedy comes in the simplest form.

Three years ago, firearms instructor John Carlin lay in bed wondering if a bright orange plastic stick no longer than a straw could stop accidental deaths during training exercises. The retired police officer from Minnesota tinkered around, formed a two-man company with his son and began selling his product under the Train Safe moniker.

"I never liked looking down the barrel of a gun," Carlin said.

A Train Safe device fits into the gun barrel, blocking the chamber and preventing a live round from being fired. It extends from the front of the barrel a quarter of...