Debunked!!!!
Check out the Box o Truth educational zone #18.... Conclusion is use brass or steel, just don't mix during a range session.
They also baked the lacquered casings for a ridiculous time at temperatures well beyond what your going to get unless your going cyclic..... The lacquer doesn't melt off guys. Like I said, google box o truth.
That said I've shot thousands of steel cased ammo through my ar15s, lacquered and not. I can hit a foot squared steel plate at 200 yards extremely reliably and rarely have any issues (jam, squib, etc). They happen but not very often, and then I welcome them as a training opportunity.
I still wouldn't use them for self defense, but they are great range rounds.
As others have already said most of the horror stories are "from a guy" who heard it from another guy who read it on a forum.
I love the stuff, mostly because I can't afford paying nearly .50 cents a round for brass ammo that does the exact same thing.
Until someone does a more definitive test with proof that it damages extractors or that lacquer melts (it doesn't) I'll continue shooting almost twice as much as I would with brass.
Of course, all of the above is worthless if your gun just can't run it. Some just can't reliably digest it, others can. Luckily both my ARs and my M&P eat it like candy.
Last note, I placed 5 rounds of tulammo 223 and 9mm into a cup of water, submerged for 5 minutes. All rounds fired without incident and all 5 223 rounds hit my foot squared steel plate at 200 yards. Good enough for me!!