Sold under the brand names AirMunition (sold by Advanced Interactive Systems) and Simunition FX, marking rounds are reduced power cartridges tipped with soft, colored plastic projectiles that splat against the target and leave a bright mark.

When used properly and with the right protective gear, marking rounds are by all accounts very safe. They are a great way to realistically simulate firefights during training.

However, at least one death has been attributed to the mistaken use of a live round in a marking round simulation.

Theoretically, it should be extremely difficult to bring a live round into a marking round simulation. Guns used with marking rounds must be modified with special barrels that will not accommodate live ammunition, but mistakes happen when officers leave the training area for court or lunch and return to the training with a live unchecked weapon. Later in the day they think that they are firing marking rounds at their buddies and instead unleash a hollow point.

There are two ways to prevent such accidents: officers must take more care in inspecting their weapons before entering or re-entering the training area or they need to use clearly marked sim guns that are specially made only to accommodate marking rounds. An example of a popular sim gun is the Glock 17T training model or so-called “Blue Glock.”

Bob Bragg, director of instructor training at the Washington State Criminal Justice Academy, is a big advocate of Blue Glocks for simulation training. “It makes it a lot harder to make a mistake,” he says. “If a student doesn’t have a blue gun in his or her hand, then we know something is wrong.”

Unfortunately, one major drawback to the Blue Glock is cost. The trainer sells for almost as much as a fully operational pistol.