Imperial Pumpkin Porter

We took a shot at brewing 10 gallons of this beer last Friday. The recipe is here: http://beersmithrecipes.com/viewrecipe/279755/imperial-pumpkin-porter-

The target OG Beersmith gave was 1.103
Our target ended up being 1.082 and I'm trying to wrap my head around how we missed it by so much.

We don't mess around with pumpkin too often and I'm thinking that might be the culprit. I wanted to reach out to you all to seek some opinions/advice.
We ended up baking 10 lbs of canned pumpkin (100% pumpkin) at 350 for 1 hour. This pumpkin then sat in my kitchen for several hours until we were ready to transfer to our boiler, at which time we threw the pumpkin in then transferred the wort on top of it. Overall, the brew process went very smooth for us and our normal efficiency usually sits around 75% - 80%.

Any thoughts?

Did you download the recipe or just plug it into your Beersmith?

I can't say for sure, but when I plug in the grain bill on my brewing software, Brewmate (which always works for me), the grain bill works out to 1.092 at 70% efficiency, 1.103 at 80% without the pumpkin.

So unless you downloaded it and saw their specific efficiency, I don't think its clear on how many gravity points they expect to get from the pumpkin, or how efficient their brewing system is, which matters if you want to duplicate the recipe.

However, assuming 70% efficiency like most recipes (unless otherwise stated), I don't think I would count on Pumpkin to give you ~10 gravity points by mashing it, let alone boiling it.

Just thinking out loud.

I downloaded it in and upscaled it which is where I saw the numbers. Nevertheless you make a good point. I appreciate the feedback!

Pumpkin can add lots of liquid volume, with sugar lower than the wort it is added to. Could that be the issue?