And, for those who don’t know, the reasons big brewers use rice, corn and other adjuncts are:
1) they are cheaper than barley
2) they convert to alcohol while contributing less body and color to the brew, resulting in a lighter-colored brew with less body, which Americans have been conditioned to desire
Commercial beers are brewed to a very high gravity (alcohol content) and unfermentable sugar level and left uncarbonated. This "beer concentrate" is shipped by railcar to your local bottling/distribution center where it is mixed to the proper proportions with filtered, carbonated water to formulate the desired beer.
The system is remarkable in it's consistency.