FYI. There is a Utube video by Jeremy Cheek testing the M1 with many types of ammo, both military and civilian. Many different bullet weights and powder types. He set up a high speed camera to record the op-rod speed with each different load/weight. Plus there is a downloadable chart that lists all the different op-rod speeds so a person can compare. He properly lubed the rifle and installed a new Orion 7 recoil spring, and used the original gas screw. Not a vented one like Shuster.
