Indoor ranges and cast bullets, is not really about the lead, but the wax used to lube the bullets isntead.
Hence shoot at a indoor range that the exhaust system in the range just sucks, and withing a few mags of waxed cast bullets, the smoke on the range from the burnt wax is so bad, your hacking black soot in hand fulls out of your lungs instead.
So on ranges with heat and A/C, they tend to not allow wax casted bullets, since it will require them to crank the exhaust system to get it out of the range before it builds to toxic levels, which in turns cost them more money to run the heat or A/C instead.
As for PC bullets, you still have a light amount of smoke from the Poly coating burning on the bullets (the fouling you will find in the barrel and gun when you go to clean it), but it's at the level of just standard jacketed bullets type of smoke isntead.