Batch size: 5 gallons (19 liters)
Brewhouse efficiency: 72%
5 lb (2.3 kg) Maris Otter
1 lb (454 g) of 10L Munich malt
1 lb (454 g) flaked oats
1 lb (454 g) Victory malt
1 lb (454 g) pale chocolate malt
8 oz (227 g) British crystal malt (45L)
8 oz (227 g) Midnight Wheat
0.5 oz (14 g) Nugget [14% AA] at 60 minutes
1 oz (28 g) Fuggles [5% AA] at 10 minutes
Wyeast 1318 (London Ale III)
Mill the grains and mix with 3.1 gallons (11.8 l) of 163°F (73°C) strike water to reach a mash temperature of 154°F (68°C). Hold this temperature for 60 minutes. Vorlauf until your runnings are clear, then run off into the kettle. Sparge the grains with 4.1 gallons (15.6 l) and top up as necessary to obtain 6 gallons (23 l) of wort. Boil for 60 minutes, following the hops schedule.
After the boil, chill the wort to slightly below fermentation temperature, about 66°F (19°C). Aerate the wort with pure oxygen or filtered air and pitch the yeast.
Ferment at 66°F (19°C) until fermentation completes. Upon completion of fermentation, crash the beer to 35°F (2°C), then bottle or keg and carbonate to approximately 2.25 volumes.
TIPS FOR SUCCESS
The one adjustment I might make is in carbonation: If you find the flavor is a little too sharp, reduce the carbonation to an even 2 volumes of CO2. You’ll sacrifice a bit of fullness in the mouthfeel, but that’s preferable to sacrificing the smooth soft character we expect from an oatmeal stout.