His skin contacts the sharp point of the handle and 2 other parts of the handle but no other part of the aga - the rest of the oven would be hotter than the handle
The issue of the burns was that the firing of the rifle did not create enough heat to cause the burns but if heated to 200c it could. The main thrust of the investigation was that the SM was not used when SC was shot. The matter of the burns was left unresolved. "It is not known how the rifle became that hot".
However there is another possibility irrespective of the base material or any plating.
Aga door handles can indeed get quite hot. If you’re experiencing excessive heat, it might be due to worn-out insulation or missing door washers. These washers help reduce heat transfer, so replacing them could improve efficiency.
Given Jane's suggestion about the lack of maintenance by the family in general this may indeed have caused the oval burn mark. Without a test as to which parts of the handle would get the hottest we cannot be certain but nevertheless it does not rule out the handle.
As well as the handle the door can become heated by other means