In order to make an oatmeal stout, unfortunately, you need to perform a real mash with base malt (2-row malted barley), otherwise you get nothing from the oats other than starchy haze. To do your mini-mash, use about a 1:1 ratio of 2-row to flaked oats. If you don't have flaked oats (this is the form you find it in at most brew shops), then you need to perform a cereal mash, which is another thing entirely.
I can't be arsed to keep up this list of what's in the fermenters, but hey, check out the cool brewery I own!
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