Just to share my experience (more accurately, my STUPIDITY) regarding the topic... And sorry for this long posting...
While back (about 5 years ago) when I had a Taurus PT-99 in 9mm, I was out shooting my reloaded ammo with 115 gr cast lead bullets.
I don't know what happened, but I guess I did something wrong when I was reloading them, like skipping to put powder into this one particular round...
Anyway, I was out shooting my batch of ammo, and one shot I fired felt weird/strange to me.
There was a bang, but the pistol failed to eject the empty case. Also, the recoil was different than usual.
Without inspecting the gun (SO STUPID OF ME!!!), I fired the next round in magazine.
Then there was a much louder report than usual, and the smoke from the muzzle was dark gray/black with harsh recoil. It was more like a puff of black/gray cloud.
"Strange---," I thought...
Then I decided to inspect the gun, and guess what... Inside the barrel got bulged in the middle.
Not enough to be observables exterior-wise. But from looking at the bore inside, I saw a clear ring of bulged bore.
I guess the previous round was weak (with not enough powder or no powder at all), and the lead bullet got stuck inside the barrel. And the next round jammed it from behind and pushed it out, creating the bulge in process due to overpressure. I was LUCKY that I was shooting lead bullets. If it were shooting jacketed bullets, it could've cause some major manage to the gun and to me!!!
Anyway, I got totally bummed out. I came home and contacted Taurus and explained what happened.
I mentioned that fact that I was shooting reloaded ammo (wanted to be honest about it), and something happened and the barrel got damaged.
Then the person from Taurus told me to send the pistol to them and they'd see what they could so.
So I did so, with explanation on the problem (shooting reloaded lead bullets and barrel got damaged) written on the service form.
I fully expected them to replace the barrel, but I also fully expected to be charged for the service.
(I was willing to pay, since it was MY mistake...)
About some time later, I got my pistol back from Taurus with a new barrel, but with NO CHARGE!!!
They repaired it for free!!!
It was totally unexpected, and to this day I talk very highly of Taurus' customer service to anyone who cares to listen.
I'm not sure if this was just an isolated case or a norm. And I'm NOT saying that Taurus should/will provide warranty service for you no matter what kinds of ammo you shoot.
But from my PERSONAL experience, I got a full warranty service for free of change while shooting reloaded ammo.
And yes, I've been extra careful since then when I reload my ammo. And I haven't had any incident after that.