I own a Glock 26 9mm. I shoot it every weekend too. I tried some cast 9mm. Accuracy was OK, lead in the barrel was minimal after 100 rounds. I stick to plated. I have five thousand of them, and shoot about 30 a week so they should last me for quite a while.
Oh and for the polygonal rifleing thing. My BP revolver has polygonal rifling. All I shoot out of it is lead. Then again the pressure is not that high either.
Note I cast my own for several calibers, and for my BP revolver. I do not shoot the Glock a whole lot due to the fact that I have several other hand guns that I do shoot a lot. I shoot the Glock enough to stay proficient with it. I carry it most of the time.
No matter how many times you do it and nothing happens it only takes something going wrong one time to kill you.