Fezziwig Clone - FG really low

So I tried my hand at an Old Fezziwig Clone. The below are the ingredients I used. So this batch finally finished fermenting but finished way low. The initial taste test is really good. I think this is going to be a great beer once it is finished aging and carbed. But I am wondering why I finished so low. BeerSmith estimated at 1.014, but I was at 1.005. I checked my hydrometer to make sure it wasn't off and it was good. I am not worried about the beer as long as it tastes great, just want to understand my process and improve where I can. Get more predictable results. (Hard to replicate a great recipe if you don't know where you went wrong/right).

Ingredients

8.75 lb Pale Malt (2 Row) US (2.0 SRM) Grain 72.92 %
2.00 lb Munich Malt - 10L (10.0 SRM) Grain 16.67 %
1.00 lb Caramel/Crystal Malt - 60L (60.0 SRM) Grain 8.33 %
0.25 lb Chocolate Malt (350.0 SRM) Grain 2.08 %
1.00 oz Centennial [6.00 %] (60 min) Hops 18.6 IBU
0.50 oz Cascade [5.00 %] (30 min) Hops 5.9 IBU
0.75 oz Williamette [4.00 %] (10 min) Hops 3.4 IBU
0.10 oz Cinnamon Stick (Boil 5.0 min) Misc
0.28 tsp Irish Moss (Boil 10.0 min) Misc
1.00 oz Ginger Root (Boil 5.0 min) Misc
1.00 oz Orange Peel, Sweet (Boil 5.0 min) Misc
1 Pkgs Nottingham (Danstar #-) Yeast-Ale


Mash Profile

Single Infusion, Medium Body, No Mash Out
60 min Mash In held at 154 for 60 min.
Mash Thickness: 1.5qt/gal



Beer Profile

Est Original Gravity: 1.059 SG
Measured Original Gravity: 1.058 SG

Est Final Gravity: 1.014
SG Measured Final Gravity: 1.005 SG

Estimated Alcohol by Vol: 5.81 %
Actual Alcohol by Vol: 6.91 %

i don't know if this helps, because i'm still a noob. i hope i don't give any incorrect advice.

dissolved sugar is assumed to be the primary thing that affects the SG. there are fermentable sugars and unfermentable sugars (unfermentable sugars are called dextrin). the more dextrin you have in your beer, the higher the FG will be.

so, i can think of two things that cause low dextrin levels in beer: low mash temp and no mashout. because of the different enzyme activities, mashing will convert more of the extracted dextrin to fermentable sugar at lower temperatures, 150 degrees and below. maybe you didn't actually mash at 154 degrees. also, for consistency sake, you are supposed to do a 10 minute mashout at 170 degrees to halt all enzyme conversion at then end of your mash. if you didn't mashout, and your mash sat around for a while before you boiled it, dextrins were getting converted to fermentable sugar that whole time, hence the low FG.

Thanks for the response. You seem pretty well informed for a noob. I wish I was half as informed when I started.

I did validate my thermometer and hydro. I barely lost a degree during my mash... and I am pretty confident that I was mashing at the right temps. I don't do a mash out but I would think that a mash out would only affect my OG. A mash out does stop enzymatic activity but it also makes the mash less viscous I believe allowing more sugars to be grabbed during the drain. Even if the I wasn't grabbing more sugars I would imagine that the only number that would be affected would be my OG. I pretty much hit my target OG, although I may be able to up that using a mash out. But not really sure how this would affect my FG that drastically (9 points). I obviously had more fermentables then I originally thought. But I thought BeerSmith was suppose to factor in fermentables and non-fermentables. I guess I can double check with the potential sugar extraction for the grains I used and see what I get when I manually calculate.

Also, if I am missing something in your original post let me know. Maybe I am just thinking of it wrong. Unless I had a better accuracy for extracting from my base malts then i did my speciatly? Then I would have more fermentables and less non-fermentables. But I milled them all together and mashed together. So not sure how that would happen.

So I did my calcs and this is what I came up with (BeerSmith appears to be on the money for efficiency and extract numbers):

Potential Extract = 431.25 (1.078)
Actual Extract = 319 (1.058)
Efficiency = 74.3%

Could BeerSmith be calculating based on a different attenuation?

My gravity measurements:
Starting Gravity = 1.058
Final Gravity = 1.005
Attenuation = 91.38%

If I would have hit 1.014 my yeast attenuation would have been 75.86% attenuation. Could BeerSmith be calculating based on a lower attenuation percent? Or am I still looking at this wrong?