Burnt Caramel Taste in Oatmeal Stout
I brewed an oatmeal stout from a kit from Midwest. I'm tasting it after a few days in the keg, and I'm getting a sort of burnt caramel taste and can't decide where it's coming from. To be clear, it's not an "off" flavor; I've tasted it in several commercial brews, namely Duck Rabbit's Milk Stout. I don't hate it, but it isn't my favorite taste, and would like to know the cause.
9 lb 2-row
8 oz rolled oats
12 oz chocolate malt
12 oz roasted barley
mash @ 152
1 oz Fuggles @ 60 min
Expected OG 1.047, actual 1.043
FG 1.016 <-- Originally used Munton's yeast (came in the box), slight krausen for about a day and promptly fell. Took gravity reading @ 3 days, 1.021. Gravity @ 7 days 1.021. Pitched rehydrated US-05 @ 8 days, swirled carboy. Gravity @ 21 days 1.016, racked to keg.
Since there's no crystal malt, I'm thinking the flavor is caused by a combination of the roasted barley and the relatively high residual sweetness (given the low OG) caused by low attenuation (about 61%). This makes sense to me, since Duck Rabbit's Milk Stout would have lactose causing sweetness, and the roasted barley might contribute the burnt flavor. Any ideas?