The spring in the Buehler safety rod is intended to dampen the slop of the wing, providing tension and thus resisting any up-&-down loose motion when the safety is 'OFF'. The Buehlers I've seen have had no screw or ball bearing in the rod's hole; actually the only screw I remember is the one that holds the wing to the rod.
I've had one FN-style left-side wing safety with a tiny ball bearing partially pressed into the rod to dampen movement, requiring some force to push into the bolt sleeve. It had a tiny detent hole inside the rod's longitudinal bolt sleeve hole, to further restain the safety in the 'ON' position. NEAT idea, I've never seen it used anywhere else.
Regards, Joe
