Does it have to be a heat gun or can I do it with a lighter?
if you have a hair-dryer, set it on high and just use that. I've done that plenty of times, and a simple dryer works wonders. :) Simply takes a bit longer, since the heat is spread out over a larger area.
Shrinking heat-shrink sleeves
in Electronics chit chat
Posted
Hope this helps!
~MMN Maniac