I've been inside a bunch of Syracuse Lefevers and have not ever seen springs to retract the firing pins. I have not experienced the problem you describe with difficulty closing the gun due to protruding firing pins.

On the older guns, you will find two small screws on the bottom of the action to adjust hammer rebound. Just going from memory, I would guess those adjusting screws were eliminated by serial number 35,000 or sooner.

A true sign of mental illness is any gun owner who would vote for an Anti-Gunner like Joe Biden.