Sometimes stove top temps aren't the best indicator of when to begin shutting down. If the wood is all flaming I will begin shutting down as long as I'm over 300°. Whodaman, make sure you're shutting down in stages, not all at once. Also you will have more success loading your stove in cycles. Having such a large firebox allows us to avoid over coaling so you can get away with burning the way you are, but you will probably have more success burning in full cycles. Glad you're happy with your insert.