It seems likely...
that yours is an older 40-X, since the sear appears to be the split type originally used on the 721/722 series rifles (pre-700). If so, the 2 screws on the front control trigger pull weight and overtravel (top and bottom screws, respectively, in your photo, which has the trigger upside down), while the rear screw controls sear engagement, which should be visible through a port on the left side of the trigger housing.
Hope this helps.
mhb - Mike
