As I check the web sites for night sights, I find no reference to compatibility with the new gen 4 guns. Can someone confirm that if a web site states G27 for instance that it will work for the gen 4's as well as the gen 3's. BTW, my G27 gen 4 has a nut on the inside of the slide under the front sight. I believe the gen 3 guns are press fitted. Is this correct? Thanks in advanced for any insight on this.