I have never really found a reasonably priced thermometer of any sort that was good, IR guns included, they are the same specs as the unit I posted. Most are +/-2ºF and some are worse. They are a useful tool as long as you keep the limitations in mind they do not really like shiny objects (smooth plastics for example) and do best pointed at something that reflects about as much light as a brown paper bag. They can give a good idea of gradients and spot temps but they cannot provide a precise measurement. They just do not work that way.

Sadly I calibrate instruments that require less than 0.5ºF in error and I have some very good thermometers and thermal couplers. The general thermometers used in the hobby are poor at best. This is why I suggest a number to be able to separate out the worst ones. I typically see a range of 2-3ºF from each other in a sampling group of 20 units the unit I linked earlier usually in 2ºF of correct (on the specs) the average is close to correct often being only 0.7ºF off.