Glock, along with some other manufacturers, claimed using copper plated bullets (grouped along with lead cast bullets) would void your warranty. I bought an aftermarket 9mm barrel with conventional rifling, partly to heed this advice, and also to switch calibers in my G23 to 9mm, to work a 9mm only assignment.
I personally now regard that idea as an old wives tale, probably conjectured before quality plated bullet (Beerys, Rainer, and others) became well established. I have never heard of anyone testing and demonstrating, the specific effect that had been theorized, using plated bullets. I do not shoot cast or exposed lead bullets (any non-jacketed, non-plated). Those put a lead mist in the air and are prohibited at indoor ranges.
I can attest to the opposing point of view. I have shot a lot of plated bullets in my Glocks in 40SW and 9mm. Both in the polygon bore and conventional rifling without noticing any leading in any barrel. I know what leading in the barrel looks like from shooting and carrying Smith & Wesson revolvers and cast wadcutters and SWCs.
I was actually impressed that when I did have one plated bullet squib lodge in the barrel, and I pushed it out of the polygon bore, it only looked slightly flattened, shiny and the plating was perfectly attached. In my Glock polygon barrels, I would not hesitate to carry Berrys Hybrid hollow points, that are plated first and then swaged to stamp the flying ashtray imprint. Speer Gold Dots do the same thing.
I also think the poly barrels are a lot easier to clean that rifled bores.
