I always wondered why they go to all the trouble of building oak barrels and scorching the insides. Why not just scorch a few pieces of oak and chuck
'em in the bottle. My best guess is that the barrel makers have a strong union.
Brew shops often sell bags of dried oak cubes with varying levels of charring for exactly the purpose of flavoring without barrels. Beer guys usually soak 'em in whiskey for a few days, then dump 'em into the secondary fermenter for a while.
They get strained out before bottling.