It is a big chunk - Wheeler Engineering Fine Gunsmith Equipment Armorer's Handgun Sight Tool

I bought it to move the sights on my S&W Bodyguard 2.0 . Those sights are incredibly tight.
The round puck that holds down the slide just barely bridges the ejection port. On a bigger gun the port would likely not be under the puck. Btw, the puck was missing the 4mm setscrew that holds it in place. I printed a puck that fits my pistol better cause I can.

The first time I tried to move the front sight I had to really torque on this and when the sight moved I heard a snap and thought I broke something. When the sight moved, it moved a lot. Some of the weaker looking pushers I saw would likely have stripped out on me.

In the manual it advises to put some load on the sight and tap on the pusher with a hammer in hard cases like mine. Also mentions wrapping contact points with masking tape. I used blue painters tape since I had a roll handy.

I opened up the pusher unit to see what the cross screw is pushing against. There are brass thrust bearings at each end. While I was in there I noticed some anodizing scraped off. Inspection of the cross nut found a big burr that was digging into the housing. The burr filed away easily as the nut is mild steel. You may want to do your own QA.