I aint no expert or owt on getting rid of punchers. Putting tulcun or tulcum powder is just what i do. Loads of people do it. i remember reading a artical in MBR i think it was, and steve petes mechcanic did it to, so it must have some effect. I always thought that when running tyres at low pressures your tyre would deform in all kinds of different shapes, and if your tube is sticking to the inside of the tyre. As the tyre gets forced in the and deforms around what every object you are landing on tube has to follow and if its sticking it is going to cause the tube to stretch in a very small localised area.