Pistol Irons & Zeroing?

I'm fairly new to pistols so please forgive me if this is a silly question. When it comes to rifle optics and irons, we zero our sights but for pistols it seems like we don't do that. I know that my odds of ever engaging someone beyond 25yd with a pistol is practically zero but is there a POA shift within that range with 9mm out of a glock 19?​I ask since I own a Glock 19 w/ factory Ameriglo sights and my friend and I hit consistently lower by an inch or two with it. The odds are that our technique both sucks but is there a chance that the sight could be misaligned from the factory?Second, if I ever decide to put an RMR on the pistol, what is the distance do folks usually zero at? via /r/CCW http://bit.ly/2IyMH8o