That person at the range is poorly informed. Jacketed or coated ammo is the preferred ammunition for Glocks.
What that person probably meant to say was that cast, uncoated lead is not recommended. Glocks with still fire with lead, but it can cause fouling in the barrel. That is why most competition shooters that reload with lead bullets tend to purchase an aftermarket barrel (i.e. lonewolf) to shoot their lead reloads.
If you post a *Hi there* in Introductions, other Members will have a chance to say Hi right back.
About your question, like others had said, Glocks prefer jacketted ammunition (what Shooter said, plus BEB and Plated bullets). Using unjacketted (bare lead) bullets will void the warranty on your Glock, and lead to cladding of the bore, which is a serious safety issue.
I just completed an 18 hr tactical training. Put 1200 FMJ rounds through my Glock 23 in a two day period. We even set up malfunctions by putting spent casings in the mag. No problems what so ever! Ya gotta love it!
So, do I understand correctly? You CAN use plated bullets in the Glocks? I recently started reloading 9mm. I was wanting to use plated bullets but could find nowhere stating that was ok. I know not to use cast. Please Advise.