I have a Jennings Machine (sightpushertool.com) sight pusher that I've used to change many sights - on a 3913, 4040PD, 5906, and some SIGs and Glocks. It's similar to many of the frame type sight pushers, and works really well - just lubricate the jack screws before pushing the sight. Setting up the alignment is tedious and critical - it's really easy to damage the sight or slide if you don't verify everything is well aligned and the slide is absolutely tight! I hold the slide in place with a thick cloth and put a thin shim (cardboard will work) over the jackscrew to prevent marring of the sight. I push one sight out first, then reinstall the new sight (jack screw moved to opposite side of frame), then realign the slide in the tool to do the other sight. For sights that are not in really tight, the brass punch method is much faster.