Most of my handguns have never had a factory round fired through them. Until the last five years the only ammunition I used were my own handloads. This includes the four Glocks that I own. I will say that I have never ran any handkloads through a R9. XR9, or my Solo's. I have used them in my PM9 and Pocket Nine though.
One does have to watch cast or swaged lead bullets in pitols with Polygonal Rifling such as Glocks and Kahrs.
I think all owner's manuals specifically forbid the use of handloads for insurance reasons. Smith and Wesson has a Tech Rep who specifically answers handloading questions and I have talked with him often.
I have found reloading to be a very safe and rewarding hobby through the years and has made me a better shooter,