I just go off the horn with Ron Norton of Inland
Ron personally assured me that the bolts on their M1 Carbines have been heat treated to a harder level than before, thus eliminaing the problems with his earlier rifles.
Ron went to the 2016 SHOT show and took two "mule" carbines as demonstrators. These samples had 10,000 rounds fired through them before attempting a "fire the rifles until they stop" torture test. This test was performed on the of firing these "well-used" Carbines without lubrication! They fired an average of 1800 rounds dry before stoppages! This leads me to believe that the "problem" with the bolts has been resolved.
Ron has, in fact, "taken care of the issue".