Question about my Jotul Oslo

Where are you taking your temperature reading? The Jotul manual specifies placing your magnetic thermometer on one of the corners of the top to take your readings. It seems like a lot of folk here at the forum like to report as high of temperatures as they can get off their stoves. On my
Jotul F 600 when I take readings from the left rear corner the temperature is 150F - 250F cooler than the reading I get with my IR thermometer when I shoot it at the top center. I usually cruise around 400F at a corner, but my IR thermometer tops out at 605F and I almost always get an "over" the max when I shoot the top center.

Yup, not only will it read lower in the corners, it will take a bit longer to get to the higher temps there, since lots of the initial heat and flame of a new fire or a reload goes straight up and over the baffle, and is concentrated on that center plate to get it pretty hot, pretty fast. An IR gun is nice, since it lets you get temps all over the stove, as well as the flue.

The temps differ a lot everywhere on the stoves surface. The temps all go up and down the same. Pick one location a stick with it. Watch out for the sticky air control. If it's not sliding smoothly, it can overshoot the fully closed position. The slide lifts up, opening the air flow. Typically the stove is well behaved, responding well to the air control. That said at 700 + degrees, it's going to take the air shut down for some time to bring the temps down.