I wouldn't bother with infrared temp gunning the shell surface. There are too many variables for that to be useful info. If you do, it should always be under 100. Best to check the basking temp using the method described in post number 18 above.I have a laser thermometer that I use to measure around the enclosure to spot check, in addition to digital thermometer/hygrometers on the hot and cold sides. I can't say that I've shined it directly on the shell surface. What shell temp do you shoot for while basking?