well im getting ready to start my long awaited reverse flow smoker. im having a bit of trouble with Dave O's formula. the tag on the propane tank reads 124 gallon water capacity. outside diameter of 24 and overall length of 70. when i calculate the tank volume in cubic inches i get 28,644. when i figure CC volume i get 30,361. how can the CC be bigger than the tank volume? all help is appreciated!