[Xaccers]

Airsoft M203 grenade.
Fires a cloud of bb's (not sure how many are in that one, but mine does 165 in one go).
Fits in those grenade launchers that go under the gun's forgrip.
Great for clearing rooms, not much use at a woodland site.
Powered by propane normally, hence the filling valve at the front.
There's a chamber inside which holds the gas, on the base is valve kept in place by steel ball bearings and a plunger.
When the plunger is pushed from behind, the steel ball bearings retract into it, which allows the valve to open and the propane escapes into the bottom of the bb channels, which then pushes the bb's out.
Makes a nice bang and gives a good cloud, but they're not very accurate due to the bb spread, and take ages to load.
If you don't reset the valve properly, when you go to fill them with gas, it leaks and ends up puffing the bb's out, wasting them and time it took to load.

Just filled with gas they make great fly swats.
Would make an interesting lighter...