Weak mag latch spring. If you want to rework a new one, you need to do three things. 1- Get a spring replacement kit from Brownells. 2- Use fine valve grinding compound on the slide rails and work it back and forth on the frame until it moves smoothly. Don't over do this step! 3- Remove the trigger, sear, and hammer. Pull the temper on each piece and polish the bearing surfaces. Then harden the parts and pull to a straw brown temper. Reassemble and it should show a tremendous improvement
