jeffnet
Welcome to the Forum.
If you can remove the trigger you may find the top surface of the trigger blade is very rough.
Using some black, wet/dry silicone carbide sandpaper and a small block of wood as a backing tool this top surface can be smoothed out which will help some.
Also, the bottom surface of the sear's arm (the thing that is sticking out from the lockplate on the inside of the lock) can also be smoothed up.
This is the surface that the triggers blade pushes against to release the lock.
If polishing theses doesn't help the problem is probably the sear springs fault.
The sear spring is the U shaped (or V shaped) spring at the back of the lock. It's lower leaf pushes on the top of the sear to engage it with the tumbler.
These springs are often made much stronger than they should or need to be.
If you feel brave you can change the force generated by this sear spring.
To do this, loosen the screw about two turns and insert a knife blade between the spring and the lockplate. This will lift a small tab on the spring out of the lockplate slot that positions it.
Once released it will swing up easily and removing the screw will also remove the spring.
Using a pair of Vice Grips, located in the same position that the lock plate would be clamp the lower leaf.
Use a small flat file to file the lower leafs outer surface to reduce the leaf's width.
File ONLY in the direction of the leaf, never across it. You want all of the file marks running only in the direction of the leaf.
You will want to taper the lower leaf from the bend to the tip that was pushing on the sear so that the end of the s pring is narrower than the width at the bend.
When the tip is down to about 1/8 inch reinstall the spring by putting the screw thru the springs hole and starting the screw into the lockplate.
Once started, use your thumb to rotate the spring down until the small tab snaps into the slot in the lockplate. Then tighten the screw.
Reinstall the lock into the gun and give it a try.
One word of warning about this.
The spring MUST be strong enough to insure the engagement of the sears tip with the full cock and half cock notch 100 percent of the time.
This is a life/death requirement that cannot be ignored in the interest of lightening a trigger pull.
The guns used by the military were never designed to be target guns and they always have heavy triggers so don't expect to get the trigger pull down much below 4 pounds.