All new pistols have a caveat warning of not using reloads. My Sig Saur P226, CZ75B, Glock, and XD40 manuals all stated the same.
Its a catch all, not everyone who reloads safetly... how many actually use a magnifying glass to inspect each piece of brass? How many actually weigh every powder charge when reloading pistol ammunition? When was the last time your powder charge was calibrated, or the weigh scale you use was calibrated by a Temmis specialist?
Because of these very questions, the manufacturers put the *reloading caveat in their owners manual. It protects the manufacturer from owner potentional negligence.
The octagonal rifling has a higher tendency to foul than regular rifling. I have used lead in my Glocks without any problems... I clean my firearms after each session so fouling is not a concern with me.
I prefer not to use lead cast bullets, the bullet lubrication smokes too much in rapid firing strings... hard to see the targets

I use Frontier, Montana Gold, or BDX bullets when reloading.