Chestnut Sweet Stout

During the initial fermentation stages of my last chestnut-based stout, my AC unit busted and I lost control of fermentation temperatures pretty quickly (S-04 is a beast and warm winters in Austin, Texas are a blessing and a curse). Unfortunately for me, the resulting product was full of unwanted phenol alcohols and unpleasant esters. Not to be deterred, I rigged up a swamp cooler setup and tried my hand at another chestnut-based stout, and man was I glad I did. This latest beer is my best gluten-free homebrew to date, and I am hoping that with just a bit more aging, I will have a product I can be truly proud of. Instead of sorghum like my last stout attempt, I used brown rice syrup as an additional fermentable source, and I added a half pound of lactose for extra body and sweetness. The lactose and molasses seem to work well in tandem for this particular brew. Also, as I simply did not have the time, I simply boiled the chestnuts first for an hour and then steeped them for about 2-3 hours instead of the standard 24 hour steep. Perhaps a full 24 hour steep would work better, but the brew seems fine with the shorter steep. In any event, here is the recipe:

Chestnut Sweet Stout

Batch Size: 5 Gallons
Boiling Time: 60 Minutes
Primary Fermentation: 14 days @ 68 degrees
Secondary Fermentation: 14 days @ 68 degrees
Bottling: Carbonated with 3/4 cup of corn sugar
OG: 1.056
FG: 1.017
ABV: 5.2%
IBU: 31

Ingredients/Instructions:

5 lbs dark roasted chestnut chips boiled for 60 minutes and steeped at 150 degrees for 2-3 hours with amylase and pectinase
2 lbs dark roasted oats steeped at 150 degrees for 45 minutes prior to boil with 1 tsp additional amylase
3 to 3.5 lbs brown rice syrup (prior to boil)
1 lb dark Belgian candi syrup (prior to boil)
2/3 cup blackstrap molasses (prior to boil)
0.5 oz northern brewer hops (60 min)
1 oz fuggles hops (15 min)
1 tsp Irish moss (15 min)
1 tsp yeast nutrient (15 min)
8 oz maltodextrin (5 min)
8 oz lactose (5 min)
1 pckg S-04 safale yeast
12 oz of cold-brewed Italian espresso coffee (added during secondary)
1 pckg of heading powder (added during bottling)

Picture of the stout after ~5 weeks in the bottle:

There was a previous thread where folks called into question the need for the 24 hour chestnut mash, so I tried boiling and then steeping with enzymes in my latest IPA. Unfortunately, my boil resulted in a lot of unconverted starch particles, which eventually settled out in my fermenter, but resulted in a loss of about a gallon of brew trying to keep that out of the keg. Did you have a similar experience when you boiled the chestnuts? I'm trying to figure out if the boil was the problem, or it was the homemade chestnut chips and the fine grind I put on them.

I actually did not have that experience. By the end of primary, there was maybe about an inch or so of trub at the bottom of the fermenter. Nothing too bad at all. I should note I grabbed my chestnut chips from Trails End.

Interesting; must have been the homemade chips.

That's a great looking brew. Anything you'd change if/when you brew it again?

If (hopefully when) I brew this again, I might actually add a little bit of cocoa and maybe up the coffee just a very small tad. There are already a few chocolate notes in the stout, but I think it might actually benefit from some more (bringing it closer to a mocha stout I suppose). That being said, I am pretty happy with it as is.

I am about to embark on brewing some chestnut beers for my gluten allergic cousin so quite interested in the outcome of your experiment.

A couple of questions I have is do you know roughly SRM of the chestnuts (just a rough guess is fine)
and also what the potential SG and finishing gravity might be of the chestnuts themselves as the recipe I got off a site had 5lb of chestnuts and corn sugar but for me beersmith thinks it will finsh around .993 so I need to use less corn sugar as it will be too dry for my cousins tastes

Any advise would be greatly appreciated