Thunder-B (Airsoft grenade)

A Thunder-B distraction device is a simulation grenade formerly manufactured by Hakkotsu and now manufactured by Valken Tactical under the name "Thunder-V". It consists of a disposable plastic shell and a mechanism for causing the shell to burst open with a loud noise. It is commonly used in the sport of Airsoft, as a distraction device similar to a flashbang grenade or as a simulated area-of-effect weapon.

As a simulation grenade which is not intended to cause harm, the Thunder-B grenade does not use any explosives. Instead, the grenade simply makes a loud "bang" sound, through the use of compressed carbon dioxide (CO₂) gas to burst a plastic shell. The core, which is reusable, is the component with the safety pin which is pulled out to start the timer. The user installs one standard 12 g disposable CO₂ cartridge inside the core, and then screws the core into a disposable plastic shell designed for the grenade. Then, when the user wishes to use the grenade, they pull out the safety pin and throw it. The mechanical parts in the core will puncture the CO₂ cartridge and begin releasing pressurized CO₂ gas inside the shell. In approximately 3 to 5 seconds, the pressure will be sufficient to cause the plastic shell to burst, releasing the pressure and producing the loud "bang" sound.

The Thunder-B grenade does not expel any projectiles, but many airsoft fields and events provide rules dictating a certain "blast radius" around the grenade, and players within that radius at the time of detonation are eliminated the same as if they had been struck with a plastic BB from an airsoft gun. Alternatively, the rules may specify that players are eliminated who are in line of sight to the device or who are in the same room. At a field or event which does not specify a blast radius for Thunder-B grenades, the grenades may still serve a tactical purpose as distraction devices. Some fields and events ban the use of the devices.

It is possible to trigger a Thunder-B grenade by a tripwire such as a fishing line tied between its safety pin and a stationary object, provided the grenade is wedged or fastened in place to prevent the tripwire from simply pulling the grenade, and provided the field or event does not forbid such triggered devices. However, there are at least two main drawbacks to the use of any triggered device or "booby trap" in airsoft. The first disadvantage is that any players who would be eliminated by a triggered device are unlikely to be in sight of a referee or opposing player at the time of the elimination, which creates the distinct possibility that the players will ignore the triggered device and continue dishonestly without honoring the elimination. The other disadvantage of triggered devices is that, on most fields, they are primarily useful in wooded sections where they can be hidden, and the owner of the device is unlikely to be able to locate it after the game in order to retrieve any reusable portion of the device.

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