A sight pusher can generate tremendous amount of force; easily 1000 lbf. That pushing force only means anything when the slide is held fast. In other words, force of similar magnitude is applied on the slide. If that force is allowed to apply to the unsupported part of the slide, the slide may collapse. Ends of the slide, especially the rear end, are self supported, but the middle of the slide is not.
The wheeler pusher is not cheap. But I myself is not very impressed with its design. The supporting pads are too small and not contoured to fit the slide profile. Worst of all, one pair of them clamp on to the mid section of the slide. I would put in a plug to support the slide if I have to use it.
A screw spreader, as highlighted by a previous post, would be my way to fix the damage.
-TL
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