Oven temp vs controller temp

Hello guys, I am new to powder coating so please forgive the noob question. I am having trouble controlling my oven temperatures. I purchased the oven from an online retailer, it’s 2x3x5 with a typical PID controller and fan. For some reason, the actual oven temp doesn’t match the temp on the controller. I verified this with a thermometer as well as a temp gun. I’ll set the oven to 400F, and the actual temp inside and part temperature is like 470F. This is making temp controller nearly impossible. I then shot my temp gun at the surface of the location that the probe is installed and the temp is exactly the same as the controller. This is telling me that probe is actually reading the temp of the metal that it’s attached to and not the air temp. Is this just the way these oven work? Thanks guys