Nudge;
As I said those two screws have absolutely nothing to do with the cocking. They enter into the cutout in the bar of the frame where the mainsprings fit & butt up against the lower limb of the spring. The cocking hook works on the axle for the hammers & is totally independant of these screws.
Another use for these screws is given in a ca 1892 catalog, page 17 under General Instructions.
"To take the hammers out--Turn in the rebounding screws in bottom of frame until the hammers are relieved from the pressure of the main springs; then drive out the pin on which the hammers are pivoted and they will drop or lift out readily." These screws "Could" have been used all the way to the end of production. They were dropped at some point, likely as a cost cutting act, but it has absolutely nothing to do with the mode of cockling.
On my guns which have the screws I keep them set where with the hammers down the firing pins set approximately flush with the breech face, have never had a problem with them firing & they give absolutely no pin drag in opening the gun.
On my large hook guns without these screws they seem to be factory set to about this same position. With the side plates off & hammers down there is a bit of free motion to the hammer. It can be pushed forward by hand to cause the firing pins to protrude but is not under spring tension at this position.
Personally I would say they are free motion at the end of their travel, not true rebounders as they do not re-compress the spring to produce the rebound. Lefever catalogs though describe them as being rebounding.
In a ca 1913 catalog no mention is made of these screws as they had been eliminated by then. however it is stated
"Lefever Locks are rebounding,avoiding danger from firing pins pressing on the primers with full force of mainspring when gun is not cocked."
I have never had to compress the mainspring to either remove or replace the hammers on a Lefever.