Guys, I just got a SIRT Pro and I'm having one hell of a time getting the front sight post installed. I'm using Ameriglo Defoor's, and the screw installs into the sight just fine when it's not on the slide, but once I put it on the gun the screw just spins endlessly (I'm using two different Ameriglo screws with the same results). It's obviously not catching the threads, but I can't tell why. Is this a SIRT problem, or an Ameriglo problem? Any insight would help.