Milsim West just came up with their grenade rules for their milsim events that each and every airsoft player planning to join in them should take note. This is a good set of rules which other event organisers can also review and adopt for their events so as to avoid confusion as to what counts as a grenade and its proper use...."All participants may carry up to 4 hand grenades.

• Hand Grenades for MSW events are restricted to 'live action' type grenades like Thunder B, Tornado, TAGs Hand Grenades, or pea grenades. Inert replica grenades (like those made of rubber) are not permitted. Tennis balls are a definite no-go!
• When throwing a hand grenade yell 'FRAG OUT' so participants can keep a look out for incoming grenades.
• Hand grenades have a 'kill' radius of 10’ from where the grenade comes to rest (not point of impact). This is particularly important when using the Tornado™ type grenades – there are too many issues of whether or not a BB spraying from these hits a participant or not, so we just treat these as if they were inert rubber grenades, but with cool effects. So no matter how far BB’s may project from the grenade itself the 'kill' radius remains 10 feet from the point of rest.
• If you are using one of these types of grenades, you must arm it according to manufacturers' instructions and then toss it. If the grenade fails to detonate, it is considered a 'dud' and has no effect on opposing participants.
• Players behind no cover when a hand grenade goes off within the kill radius are considered 'wounded' and must follow 'healing' procedures.
• Participants behind soft cover (Bushes, Shrubs, Grass, and Small Trees) are 'wounded' and must follow 'healing' procedures.
• Participants behind solid cover (rocks, hills, bunkers, vehicles and trees much larger than their body) with the cover between them and the hand grenade resting place are considered alive.
• If a hand grenade is thrown, hits an object, bounces back, lands and detonates near the thrower, they along with everyone in the 10’ radius are 'hit'.
• If a hand grenade is thrown into a room and detonates, every participant in that room is considered wounded whether they are hit with BBs or not. You may kick the grenade out of the room before it goes off or pick it up and throw it back. However, this is not Act of Valor. You may not dive on the grenade to save your buddies. Please stay safe.