McKraken, Good job.
After three or four attempts, I'm still looking for that velvety smooth taste that comes from the Youngs Double Chocolate Stout and it's tough. Funny, I had a Youngs last night and it's still as satisfying as the first time I had it.
I see you put a pound of lactose in yours. I think the general-tolerable guideline is about a pound for 5 gals.
The astringency you're describing could be coming from the cocoa powder.
I know I've had some chalky taste from the cocoa powder and I don't use that ingredient anymore.
Also depends on when you added the cocoa powder during the boil it and how you added it.
Ex: Did you just put the cocoa powder directly in the boil or did you take a cup or wort from the kettle and mix the cocoa powder with the wort, stir and then dump in the boil, etc.
Can't wait to try it.