Estimated OG

Hello,
I have searched and read many threads but still cant seem to get my Estimated OG to where it should be.
I have a recipe that when at 70% efficiency will yield a 1.052 OG
When I enter in this recipe and set the brewhouse efficiency to 70% beersmith is showing my OG estimate to be 1.062. This is not the 1.052 That I expected.
I had a friend run this same recipe at 70% efficiency on another brewing program and he came up with the numbers that I was expecting ie 1.052.
Your help is appreciated.

Here is my sheet.

Type: All Grain
Date: 3/1/2008
Batch Size: 10.00 gal
Brewer: 
Boil Size: 13.00 gal Asst Brewer: 
Boil Time: 90 min  Equipment: 90 - 10 90 min boil 10 gallon batch 
Taste Rating(out of 50): 35.0  Brewhouse Efficiency: 70.00
Taste Notes: 
 
Ingredients

Amount Item Type % or IBU
19.00 lb Pale Malt, Maris Otter (3.0 SRM) Grain 78.32 %
2.00 lb Brown Malt (65.0 SRM) Grain 8.24 %
2.00 lb Caramel/Crystal Malt - 40L (40.0 SRM) Grain 8.24 %
1.26 lb Chocolate Malt (350.0 SRM) Grain 5.19 %
2.50 oz Fuggles [4.50 %] (60 min) Hops 19.5 IBU
1.00 oz Fuggles [4.50 %] (10 min) Hops 2.6 IBU
1 Pkgs London Ale (Wyeast Labs #1028) [Starter 1000 ml] Yeast-Ale 


 
Beer Profile

Est Original Gravity: 1.062 SG
Measured Original Gravity: 0.000 SG
Est Final Gravity: 1.015 SG Measured Final Gravity: 0.000 SG
Estimated Alcohol by Vol: 6.18 %  Actual Alcohol by Vol: 0.00 %
Bitterness: 22.1 IBU Calories: 0 cal/pint
Est Color: 27.7 SRM Color: Color 

 
Mash Profile

Mash Name: Single Infusion, Medium Body, Batch Sparge Total Grain Weight: 24.26 lb
Sparge Water: 8.33 gal Grain Temperature: 72.0 F
Sparge Temperature: 168.0 F TunTemperature: 72.0 F
Adjust Temp for Equipment: FALSE Mash PH: 5.4 PH
 
Single Infusion, Medium Body, Batch Sparge Step Time Name Description Step Temp
60 min Mash In Add 30.33 qt of water at 165.9 F 154.0 F


 
Mash Notes: Simple single infusion mash for use with most modern well modified grains (about 95% of the time).
Carbonation and Storage

Carbonation Type: Kegged (Forced CO2) Volumes of CO2: 2.4
Pressure/Weight: 21.6 PSI Carbonation Used: -
Keg/Bottling Temperature: 60.0 F Age for: 28.0 days
Storage Temperature: 52.0 F 

Well,
  You can do the calculation by hand to verify it:
    From Ray Daniel's Book Designing Great Beers:  # of Gravity Units (GU's) for a malt = (points for malt) * (pounds) * (efficiency)

    For example Maris Otter has a potential of 1.038 or 38 points, so 19 lbs gives (38 * 19 * 38) = 505 GUs
    - The brown malt is 2*32*.7 = 44
    - The caramel malt is 2*34*.7 = 47
    - The chocolate malt is 1.26*34*0.7 = 30

  The grand total for your beer is: 505+44+47+30 = 626 BUs

    Now we just divide the number of GUs by the number of gallons (again from Daniels):
      626 / 10 = 62.6 points for the final brew which is 1.063 (if I round it up)

  So it appears that BeerSmith did the calculation correctly (hard to believe I can still do it by hand myself).

  If I had to guess, I would say that the difference is likely that the other program is using a lower potential for the various malts (Maris Otter in particular has a higher potential than most pale malts) or that the program is using efficiency in a different way (for example taking our trub losses into fermenter away afterwards rather than including that in the overall brewhouse efficiency).

Cheers!
Brad