...I can't imagine you can totally straighten a bent barrel.
Nearly all the barrel makers straighten barrels , usually before final turning. This is done in a hydraulic straightening jig.
http://www.ahlmans.com/customriflebarrels.html
Premium Grade
When the long hole is initially drilled through the length of the barrel, 90% of the time it has a slight curve. The barrel is then mechanically straightened before final turning. When excessively heating the barrel by "Rapid Firing", the barrel tends to return to it's original curved condition. It then moves back to straight when cooled. This can cause groups to "walk" slightly as the barrel heats up and cools. Barrel companies set aside the 10% of barrels that were drilled so close to perfect that they didn't require straightening and stamped these "Premium Grade". Therefore, a premium is no better steel. It basically means "unstraightened". For hunting guns, and heavy barreled guns, it should be considered.
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