Ok had a great start up today with this insert.my question is how can I get these temperatures up beyond 300 degrees ? I put a Rutland magnetic gauge on the top shelf as far back as possible & did cross check with my infered gun. It was very close to what the mag read.300 ish stayed for about 1-1/2- to 2 hours& after that it started to decline. So now i did a reload ! The firebox will take 16"EW& 14" NS. Should I shorten the wood to get more in ?am I doing any thing wrong ? Help please