That's why I don't use *OSFN 'universal' sight pushers.
(* One Size Fits Nothing.)
That slide would have been properly supported in a smooth jaw vice.
And the sight could have been changed safely with a nylon or brass punch and a small hammer.
rc
Was changing the rear sight and didnt quite have it secured in the sight tool properly.
Aren't stock Glock sights plastic? Be pretty hard to break anything moving them around.