If the factory cocking handle comes loose it can cause damage to the hammer or receiver. The best way to install the factory cocking lever is to degrease the cocking lever screw hole and screw. Add one drop of red, high strength, locktite to the screw and install it. Tigthten it as tight as possible, then while still applying torque to the driver rap the driver handle with a mallet several times creating an "impact screwdriver" effect to further tighten the screw. Let the locktite cure overnight, My unbreakable cocking handles installed as part of a full tune are 1/4" stainless steel studs, definitely stronger than the wimpy factory 4mm screw.