I have installed dozens of sights by using a c-clamp over the top and several leather (old belt works well) pads. I clamp as near the sight as possible to prevent twisting when drifting them in. Sight should slip fit about 1/3 of the way into the dovetail. Brass punch, small hammer and patience. Use a witness mark so you can see starting point. At 5 yards shots should all be touching, in my opinion. Magnify the 5 yard groups by a factor of five, and that is what you can expect at 25.