Bearings don't fit (Drill rod) shafts ?

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We have bought 1/4", 5/16" & 3/8" "Drill Rods" to use as shafts. They seem to measure to be exactly to size. We bought EBC bearings for this shafts and none of them fit. For example the 5/16 measured ~ .311 while the drill rod measured 0.3125. Am I supposed to be reaming the bearing up to 0.313 or something or did I buy the wrong rod. Not sure its possible to downsize the hardend Drill Rods with our equipment. Is there some shaft type that is specifically designed to be a few thousand under its nominal diameter ?

Just to make certain, I am not aware that I bought "unground" bearings but I always assumed "unground" referred to the bearing race, nothing to do with the ID of the bearing. Anyone know for certain what "unground" refers to ?