Gravity calculations between extract - partial settings?

Hi all,

I am confused about how Beersmith is performing gravity calculations when changing through the different mash settings: Extract - Partial Mash - All Grain.

I made a few test recipes, each with only one ingredient.  One was with just 8# Pilsen LME.  Another was just 8# Corn Sugar.  The confusing thing is, when I switch between extract and partial mash the gravity changes!  There are no grains in these recipes, how can this be? 

The gravity is always greater when in partial mash/all grain settings.  For example in extract mode, the estimated OG is 1.067 (for the 8# corn sugar recipe).  When in partial mash mode the estimated OG is 1.074.  What is happening?

BeerSmith assumes that the user is sufficiently knowledgeable enough to choose the proper recipe type when designing a recipe.

When you progress from Extract to Partial Mash or All-grain, the program uses the equipment profile which includes losses in the mash tun and the mash efficiency, which is back calculated from the total or brew house efficiency.  Because it is calculating back from the total efficiency, the program will assume that the sugars can be pulled from the mash tun to make up any difference and it is up to the user to check to make sure the mash efficiency is in the proper range for their process.  This mash efficiency calculation is not used at all in an 'extract' recipe, where the program does not calculate any mash sugars at all and applies a steeping efficiency to any grains which are in the recipe to calculate the sugars which would be available from that source.