I am building an ICF house and in amongst all the gear was a foam gun (and 48 cans of low expansion foam). There were no instructions with the foam gun. I am quite happy with all the procedures for loading and changing cannisters and how to clean it. My question is whether you need to use some sort of extra nozzle on the end of the gun to protect the ball at the end or whether you just stick the needle where you want the foam and pull the trigger?