The factory sight pusher is O.K. IF you are only planning on removing/replacing stock, factory plastic sights.
For any other application, a sturdier, heavier duty tool is a much better bet.
I have installed Meprolight night sights on a couple of Glocks using the factory tool.....
I've also dated a few ugly girls & drank some cheap beer in my life.
NONE of these are things I would prefer to do again.
For any serious work, I'd suggest the Meprolight sight press. It's expensive, but it will work on any known pistol slide except a Desert Eagle.
And I have changed sights on a D.E. but it takes time, a sturdy bench vise with padded jaws, a couple of brass drift punches (you WILL ruin a couple in the process) and a 2# hammer isn't overkill for this job !
NRA Endowment Member, NRA Certified Instructor for Rifle & Pistol, Illinois State Rifle Assn. - Life Member, GSSF Life Member,N.R.O.I. level I, IL Glockers #34
G: 19,20(x2),21,22,23(x2),24,27,29,34,35 & 36 (still counting)