Pneumatic airsoft grenade.

[Marffy]

A modified version of my combustion grenade. A sprinkler valve opens after a certain amount of time after the button is pressed. The valve sends air out to push the bb's out.

[roboman]

Oh boy! Throwing pressurized pieces of PVC pipe at people!

Maybe not the best idea... It would definitely work for a landmine, though.

[grock]

like roboman said, anything you might throw anywhere near a person should be light. even if you dont intend for it to hit someone, people happen to pop out at inconvienient times. not to mention that this thing would be close to a foot long, and without a high pressure source, not that powerful. you might want to check out davidvainis burst disk cartridges, its like a giant shotgun shell, but they deal out some serious pain when packed with ~50 bbs at 15ish yards.

you could try modding this for airsoft

heres a land mine that is pretty effective, but a electrical pressure switch might be easier to rig

EDIT #2 formatting stuff

[roboman]

I was more worried about the shrapnel... Assuming you're planning to make that out of PVC, as soon as it hits the ground, it will explode, shooting large pieces of shrapnel into people.

[iknowmy3tables]

well you can throw a pressurized grenade, however this longer less stable structure with excessive weight and no padding is prone to break while a lighter more compact design probably wont even without padding, though padding is a must for actual use

[roboman]

I'm not saying you can't throw it...I'm just worried about what will happen when it hits the ground. That design could be made to work, but I certainly wouldn't want it thrown at me...