The site has been changed from "Don't use titegroup" to "don't use any of the 15 fastest powders on this chart". Since Titegroup is #15 on the chart I'm guessing that's why they specify the first 15. I've never noticed the cylinders getting especially hot but that may have to do with our shooting styles. I shoot outdoors, slow fire (typically), single action. So even though I'll go through 300+ rounds at a sitting it may be over a longer period of time.