Clamp the very end of the bbl tight in the vise as Protocall says.
Even if you have to tilt the gun somewhat to be able to get the muzzle end down in the jaws and the front sight as close as possible to being clamped as well.
The idea is to bot have any vibration.
Brass punch, or steel. Sometimes a simple flat faced block of hard wood like maple will do the trick.
Generally you need the metal punch.
Often I slip a fired .22LR case over the end of a certain steel punch I have that fits nicely. The brass helps keep the sight from damage and the punch is just right for the job.
Use a big enough hammer,,this is one job where a small light weight hammer will actually do more damage from repeated failed strikes and possible mis-strikes than 1 or 2 well placed heavier blows.
Place a small mark on the sight and bbl,,a 'witness mark'.. before you begin so you know where the sight is to start with.
Swipe both the edge of the sight and the bbl surface with a Sharpie and then place a pencil mark that intersects both the bbl surface and the sight.
Then when you start punching the sight around, the displacement of the mark on the sight one way or the other will show you which way you moved the sight and how much.
Otherwise you'll be guessing and trying to imagine how much it moved.
'...It felt like it moved that time,,I think it move a little !.....
Some sights can be really tough to move like Dewalt mentions. Like they are welded or Threadlocked into place.
Others will take some efforts but will move.
A few especially if the moveable blade is a plastic or other synthetic will sometimes slide around with little effort and the biggest problem will be to find some way to tighten them into their dovetail.
I've never cared for universal type Sight Pusher tools. But some made expressly for a certain firearm work well I guess. Still like hammer & punch better. Not a gadget type guy.
