I've used several different sight pushers over the past few years and have just gotten the one sold by www.sightpusher.com. It's very solid and works like a champ. At $59.00 shipped it's a bargain. It was in my hands 2 days after I ordered on line. So far I've used it on a Sig, a H&K and an Fn.
I had been using a B&J Machine 500 for several years and it was just too easy to have it slip out of adjustment. It also was difficult to set up.
Hope this helps.