Improved and innovative methods of manufacture were constantly sought at Springfield Armory. This period model of a barrel rolling machine combines several steps in making a barrel. Note the enlarged indentation in the grooves which permitted shaping the squared breech while rolling the round barrel.
Springfield Armory NHS, US NPS
<a rel="nofollow" class="external text" href="https://www.nps.gov/spar/learn/historyculture/images/case_62_roller.jpg">Springfield Armory National Historic Site (U.S. National Park Service Official Web-site</a>