the simplest but still not very small (and very dangerous) is to use a railgun method of acceleration. of course you need some metal (like a small pin) to be in the ice, but after that, ur good to go.

the thing is due to terminal velocity and normal drag force applied by the ice surface, the range of the bullet wont be far.

but what if it was very impure water, like some substance holding the water together, imagine those small jelly water balls travelling at 300m/s. they hold shape better. and they definitely dont leave a damn trace.

bit of calculations : max initial velocity of a 4mm jelly ball. (rough est.)
=sqrt((2x9.81x)/(1.184x4xPix0.004^2))
= 287.03 m/s
~bout 260-270m/s (max initial velocity) after taking into account drag constant.

so, it can travel bout... (yadda yadda yadda..) ~ 0-20 meters effective range. (kinda near right)

hmm... so. all we need is an explosive behind it and 'water shotguns' will be a reality.

Air guns would work well too, but speeds will only reach about 140m/s. basically same principle as paintball gun.

This post has been edited by rafazafar: Mar 21 2010, 02:31 PM

that could work actually, but we need to apply the railgun method.. huhu. kinda interested in making one actually..

very true, you probably have to make it yourself and dismantle it immediate after usage n find somehow to hide it.

Laser gun.

heat from railgun can be negated by the system, but still pumping in mega amps isnt easy.
, another way is actually a system that can launch a bullet or something way up into the air and acts like an artillery.

put seriously laser isnt a bad idea, a very super efficient reflector can do the job of focusing and killing.