Well we set up the correct choke reaming tool and start cutting 0.003 to 0.004 inches of steel out of the choke with each pass of the reamer ..... we stop cutting when the barrel wall thickness at the choke area gets to about 0.022 inches .... sometimes there is very little metal that you can remove before you reach a wall thickness of 0.022 inch but you can usually open the chokes some ..... posted by Jent.