and the yeasts ability to hold up against alcohol stunting or killing it.
so, yeah you can't really increase attenuation by adding oxygen or swirling or yeast nutrient.
it'd be like trying to make a grown man who's 5feet tall be 6 feet tall....just doesn't work.
Primary: English Mild
On tap: Pale Ale, Lancelot's Wheat, English Brown Ale, Steam Beer, HoovNuts IPA
Bottled: MOAM, Braggot, Raspberry Melomel, Merlot, Apfelwein, Pyment, Sweet mead, Cabernet
Gal in 2009: 27, Gal in 2010: 34, Gal in 2011: 13, Gal in 2012: 10