Summary
A defence engineering firm in Cardiff, Wales has developed a cannon (actually more of a compressed air mortar) that fires bottles of water.
Whilst this may at first appear to be utterly useless, it's worth bearing in mind that this is a 22kg high velocity projectile that disintegrates on impact into essentially harmless debris and can be used to breach walls, doors and the sides of vehicles at minimal risk to bystanders (like an entry team) or anyone inside (like hostages).
In some ways this is just an innovative rehash of old technology - the Germans deployed air mortars in The Great War and the water ejection principle is used as countermass in several modern recoiless weapons - but putting the two together has yielded what may be a useful development.
If the company in question can only avoid being bothered by peace activists, things should go well.
Source
According to the BBC … but probably credible anyway.
Game and Story Use
- In itself an amusing bit of kit for the PCs who have everything (albiet probably those in a law enforcement role). Also good for gagetteers.
- You could probably make a case for an aerospace bomb version - streamlined water container with a paveway kit anyone?
- If you're okay with a top-attack just pushing one out of a helicopter might be quite effective - as long as it accelerates up to enough speed to burst on impact, otherwise you might as well just drop a rock on them.
- Still likely to be fatal if the container hits a person (or at the very least to mash any intervening limb).
- Possible non-weapon uses as well, e.g. for emergency entry by firefighters - especially in hazardous environments where conventional breaching tools might generate a fire or explosion.