Round up or down accordingly. Its not how much you have used yourself, but how much do you think is the upper limit on making a "good" big stout/beer. The batch size is 5 ga. Round up or down, i.e. 1# 5 oz is 1.5#. Count all types of roast not just roast barley, but chocolate malt, black patent, roast wheat etc.
Well you can't skimp on them, so I'd say at least 2 lbs (4 seems a bit extreme tho). And, thanks to one of my experimental 2g batches, I can see that (for my tastes) roasted grains are key, and grains like special-B should be skipped or used in exceedingly sparing amounts. The more I do reviews and the more I brew, the more specific I can get about what I like. Beers like Yeti (regular, oak aged being my favs, although all are good) are the shit when it comes to imperial stouts. Anything with more than the first five people in reviews mentioning raisins I could probably do without (tho they are not all bad, just that my preferences are what they are).
Lbs mean nothing to me, percentage is what's important, and for an RIS I'm looking at a minimum of 10% dark roasted grain and have gone as high as 20%. I've brewed stouts with OGs of 1.120 that called for 2 lbs of roasted barley, 2 lbs of chocolate malt, and 1 lb of patent malt....so at 5 lbs I guess I'm off the scale of your pole. I see people saying 1 lb of roasted barley as the max for an RIS...I use that much in a 1.045 Irish dry stout, so for me it definitely wouldn't be enough for something double that gravity or more.
I'm with HB42. I brew a RIS with 2# of roasted barley, 1.5# combined of 2 different chocolate malts, and around a half pound of Black Patent. Along with some darker crystal malts too. Percentage wise, I like around 15% roasted grains.
Can you post that 1.120 OG imperial stout recipe? IIRC is this the same beer that you said that you aged for a year and it turned out pretty well?
I like 70% base malt, 10% max roast/black patent etc then 20-30%% from brown/amber/crystal/sugar depending on what way I want to go
