I wonder how many farmers surveyed reported the same as they do every year?

They have 100,000 bushels of storage on farm and its all full, so they report 100,000 bushels to the USDA

Being the corn is only 52 pounds per bushel, instead of their normal 56, did they figure it out

100,000 bushels times 52 equals 5,200,000

5,200,000 divided by 56 equals 92,857.14

So if the farmer farmed 500 acres and thought he had 200 bushel per acre corn

he really only has 185.7 bushels per acre and won't know it till he empties his bins

Also pknoeber since people only refer to bushels because grandpa did it, show me when you report yields to insurance, FSA, USDA, etc. where you report it in pounds and not bushels. 

Yes 250 bu/ acre is 14000lbs per acre once its wieghed across a scale. In the example above 7.2% difference from being wrong on test weight, so if your corn is in your bins and not weighed and your assuming 56lbs and its only 52lbs you might only have 232 bu/acre.