I would like to reinforce what everyone has told you. A temp gun is a tool, not the be-all / end-all of tuning.
If you learn to tune for performance by listining to how the engine sounds, watching how the vehicle preforms and watching for a smoke trail you'll be a FAR, FAR better tuner than someone who tries to "chase a temp". Use the temp gun to check your engine from time to time but do not rely on it to tune your engine, believe me, you'll be a lot less frustrated and know about your rc that way.