In his book "Hatcher's Notebook" pages 101-2, General Hatcher described a test he made with regard to chamber wall thickness. He had the barrel of a Springfield rifle turned down until the chamber wall thickness was 1/8" (.125") and fired it with regular and high pressure (75,000 lbs/sq./in) cartridges. This produced no visible results, so he proceded to have the barrel turned down to the point that the chamber walls were only 1/16" thick (.0625"). The barrel was unaffected by regular service cartridges, but a 75,000 lbs/sq./in. cartridge blew a piece out of the side of the chamber. He remarked that since the thickness of the regular barrel over the chamber is 5/16" "it is plainly evident that the strength should be sufficient."