i have been done three 10 gallon pilot batches and a 3 bbl maiden brew using a combination of us-56 yeast and rahr 2-row malt. i have also been using oxygenation and pitching dry yeast at a rate of about 500 g yeast /125 gallons wort (22 g/5 gallons for pilot).
i have been experiencing attenuation of over 90% even with 10% crystal malt. i have never experienced this kind of attenuation. with all the improvements in my pilot and commercial brewing over homebrewing, i'm not sure what to attribute these attenuation levels, if anything.
is this a normal attenuation level for us-56? could the rahr malt have something to do with it? i don't mind the attenuation, its just a different issue than i've had with most of my homebrewing which typically seemed somewhat underattenuated.
Apparent attenuation? Actual attenuation? chico is a good attenuator
Coincidentally enough I just used the US-56 in a batch (10BBL).
I had a pretty decent apparent attenuation of 86%. We're in the "cool conditioning" phase as I like to call it, so it may drop a point or two more.
Your higher attenuation may have to do with your high pitching rate. Over double what I would deem optimum. Over pitching can lead to other flavor issues as well. I would recommend dialing down the pitching rate to the lower end of what Fermentis recommends, say 60 g per BBL. See if that improves the situation / flavor profile.
But if you love the beer as is, and that's the important part, keep it all the same!
Jolly Pumpkin Artisan Ales
We use US-56 for a range of different beers, and I see attenuation going from 66-75% attenuation depending on the mashing scheme and recipe.
We pitch at a rate of 75 gram/HL at 17-20 deg. Celsius and let temperature rise into the mid-twenties (we do no apply cooling to our FV's). Fermentation is usually done in 3-4 days.
Hope this helps, as I feel the US-56 is a pretty good yeast, and using dry yeast is just so damn convenient!