I've noticed that a lot of people have trouble getting their standard name-brand 9V battery to fit in the 09 SLG. They assume that when the battery doesn't make contact with the prongs, their battery is too small and therefore they need to shove cardboard under the battery. Well, this is not the correct solution. What actually needs to be done is you need to bend those prongs out a little bit (gently) so that they aren't quite so close to the top of that compartment. That way they make contact with the battery without the use of cardboard. By putting batteries in and out of the gun, those prongs will eventually will get pressed up to the top of the battery compartment, making it difficult for a 9V battery to make sufficient contact with those prongs. Like I said before, all you need to do it bend those prongs downward just a little bit and you're gold.