Can someone explain the differences in OG I am getting

I just stared using the Beersmith program. Great program. After I listed the grains and malt for my scottish ale, the OG recipe estimate (1.069) is about 0.020 more than the style OG and what I got (1.050). Why is that? Did I not sparge enough? I am only doing a partial mash if that makes a difference. My FG estimate was right on with what I got (1.018). what do you think?

You just got poor efficiency. The estimation in beersmith is based on what is in the "Brewhouse Efficiency" box.

There are plenty of reasons for poor efficiency. Sparging is one... incomplete conversion is another. You can use iodine to check for the presence of starches in your wort (indicating incomplete converstion). Maybe you didn't wait long enough for conversion to happen, or the temp was too low/high.

Any DME used? I am only on my 2nd batch however I was told by a few guys on this board that any steeping should not go over 170 degrees or all of the fermentables would not be released, hence a lower OG.

Can you post the recipe? That should tell us where the difference is.

Hey Brad-

Here's the recipe and how i did it.
7lbs amber malt; 1.5 crystal 75, .25 peated malt; .5 dark munich; .25 carafa II, 1 flaked barley; .5 golden promise. 1 oz pearle; 1 oz tettnanger; edinburgh ale yeast

bring 4 gal to 155. put grain bag with all grain in wort and steep for 1 hour. take out, sparge with 3 qt of 155 degree water into the wort. pour in amber malt and bring to low boil. at boil of 170 put in pearle. at 35 min, add tettnanger. at the 1hour mark, take off heat. put in ice bath. transfer to primary. top off wort with cool water to reach 4.75 gal. at 75 degrees, pitch yeast and take OG reading. cap off with blow off tube. keep at 70 degrees

I think your problem is almost certainly that you didn't stir enough to mix everything up before taking your gravity reading. Even if you got nothing out of the grains, you would end up with a higher gravity than you got just from the extract.
I also think that using 4g water to mash 3.5 lbs grain is too much water. (4 qts would be much more reasonable.)
You probably got something pretty close to the forecast value, but you measured a diluted sample which would obviously have a lower OG.

RDWHAHB

-a.

I'm with ajf, sounds like a mixing problem. As for Beersmith perhaps being off, with all the grains plus the extract it sounds like it's probably right. Because you mashed so extremely thin however you most likely didn't get enough conversion which will also cause your OG to drop.

Read up on mashing at How to Brew - By John Palmer so you can get a handle on the water amounts you'll need. ~1.3qt/lbs is a really good number for most brews. Then you can sparge to get up to your 4 gallon pre-boil volume if you like.

So how is mashing different than mini-mashing? I'm a little confused there. If recipes are generally for 5 gallons, where and when does your amount get to that level? I'm such a beginner.

The only difference between mashing and mini-mashing is that you add extract to the latter once you get to the boil. Other than that all the same rules and procedures apply.

So you will want to use the correct amount of water for your mash (say around 1.3qt/lbs) and then you can sparge with whatever amount you need to get up to your pre-boil volume.