I'm one of the advocates of ammonia solution (it irritates the nose and eyes, and it smells like urine to a dog so even when only in close proximity to the nose of the dog it confuses them (challenges their social status). However, I don't use a water pistol - the stream is too delicate and it could be confused with a gun promoting hostility by dog owner. I use a Vietnamese hot sauce bottle (Sriracha chile sauce available from your local Wally World or oriental market). Enjoy the sauce then just carry the soft bottle that has a greatly restricted closable spout that can be pointed accurately. Dogs are more confused than irritated and they have always stopped chasing when I use the diluted ammonia water technique. I don't want ammonia water in anything that looks like a water bottle - an accidental ingestion would not be pleasant. Tom