I plan on making the Dry Irish Stout from the recipe section this weekend but my LHBS is out of Flaked Barley and is having trouble getting more with the quarantine restrictions and all. Is Flaked Wheat an acceptable substitution?
Flaked barley definitely has a unique flavor that is different and more prominent than flaked wheat. Flaked barley works in a stout, but I found that it's too assertive in less roasty beers. I do commonly add a bit of flaked wheat to my ales to add a bit more body and mouthfeel without flavor effects.
Yes, you can substitute the flaked wheat, but it won't be the same.