Motion System Design

Air-powered pepper pistol packs potent punch

Personal protection has been vitally important to humans since the beginning of time. And when events like the recent Virginia Tech shootings make people question what it means to feel — and be — safe, the desire for self-defense takes on new urgency. Yet there's an enormous rift between those who believe concealed handguns make us safer and those who don't — hence the raging gun control debate. For a less controversial alternative, arming with pneumatics and irritants instead of gunpowder and lead, check out the non-lethal IM-5 launcher from Security With Advanced Technology Inc. (SWAT), Westminster, Colo.

How it works

Each shot is propelled by an individual, nitrogen-based gas canister, five of which are arranged in a “revolver” format at the back of the launcher. Pulling the trigger releases a puncture device that pierces a cylinder, causing a high-pressure explosion that propels an irritant-filled ball; automatically, the revolver indexes to the next canister. A spring-fed tube magazine along the top of the launcher feeds rounds into the chamber, a semi-automatic process that cycles as fast as the trigger is pulled.

Back story

The idea of creating a powerful, effective, and non-lethal weapon was a collaboration among safety-minded inventors, Rob Alek, Michael Cox, Billy Matthews, and Scott Sutton.

As the team began investigating the non-lethal market, they discovered some compelling statistics. They found that large numbers of people (tallying records from hundreds of thousands of searches) were typing phrases like “self-defense” and “personal protection” into online search engines. The team was equally surprised by the lack of high-quality self-defense products available to meet the demand. This inspired them to develop a protection device with teeth as well as the “cool factor.”

Design challenges

Two major challenges surfaced during product design, both involving velocity. “The problem with going to a small, lightweight projectile, which was good for velocity, was that it lacked the payload we wanted,” explains Michael Cox. “We also struggled with the short barrel length. It didn't impart enough velocity to the ball for the desired kinetic impact.”

The design team solved the first problem by putting four times the active ingredient, PAVA, into the live rounds. This causes the effective cloud associated with the payload to grow exponentially larger.

Getting the desired velocity from the short barrel required a little more engineering. The solution employs a pneumatic innovation in the air-handling system that precisely controls expansion and launch timing, optimizing the effect of the available compressed gas. Adding one or two milliseconds to the launch event gives the IM-5 the velocity it needs.

Another design improvement omits seals traditionally employed in air guns. Most air guns are based on a complex assembly of parts, including a bolt, expansion chamber or regulator, gas cylinder puncture pin, seals, and O-rings. The IM-5, on the other hand, is simpler. The barrel itself acts as the bolt, puncture pin, expansion chamber, and gas piston, eliminating seals and O-rings — parts prone to failure due to fatigue, extreme temperatures, or long-term storage in places like a car's glove box.

Design impact

The IM-5 debuts this month at $299. SWAT is also developing a weapon conversion unit that allows firearms to safely shoot training projectiles, and a non-lethal launcher for military/law enforcement use, which delivers a pepper-based projectile from more than 300 feet for crowd control scenarios.

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.