Reducing the front hump increases the sear engagement in the second stage. Good to know if someone has over-mothered the sear engagement of the second stage to the point where the second stage has been lost. You can usually recover the second stage by slightly reducing the front hump.
Originally Posted by Gus Fisher
What a lot of folks don't appreciate is that there is a lot of vertical "slop" in bolt fit with WW II parts and that makes it difficult to get a good crisp second stage with no creep. The sear will tend to drag the bolt down as the first stage is taken up, esp. if there is no cartridge in the chamber. If the second stage engagement has been mothered to an absolute minimum engagement and tested on an empty chamber, the shooter can get a surprise if there is a long cartridge, neck sized cartridge, or a cartridge with the bullet jammed into the lands in the chamber. This restricts or reduces the vertical movement of the bolt somewhat as the trigger is pulled and can cause the second stage to be "lost" when a cartridge is chambered. Years ago, when most of the rifles extant were original or at least competent arsenal rebuilds with mostly pre-war parts, I seldom saw sloppy bolt fit like I'm seeing it today.
USN Distinguished Marksman No. O-067