doug2500 wrote:A workmate suggested buying the telescopic water gun then replacing the water line with an airline as it looks like it just runs down the centre. That might be best.
Well, it'll only cost you about fifteen quid to find out (Ebay, etc), although that includes a 6 metre water hose which you won't need. Check that the thread going into the gun is a suitable size for your airline. I'm pretty sure you can buy adapters.
There are two basic types of lance extension. One has a circular aperture for straightforward jetting, and the other has an adjustable aperture with two flat "jaws" which can be set to give a wide spray. I'd imagine that the first of these would work best. All lance extensions fit with a kind of bayonet arrangement, invaiably made of plastic with a neoprene ring seal.
There are alternative ways of getting an air blast, of course. Many garden/wet and dry vacs have a leaf-blowing function. And I often use my heat gun (on cold, or indeed hot) to deliver a bit of oomph to my barbecue. Better than the wife's hairdryer, because the metal nozzle doesn't melt in the fiery glow.
BJ