Clays is a very fast powder to be using with anything but the lightest bullets and mild loads. Because of the burning speed, and if you are building stout loads, tiny increases in powder charge, or reduction in OAL, will result in huge jumps in pressure.
So you answered your own question, it is too fast for heavy bullets. Clays is best for minimum loads in 9mm and 40. I was using Clays for 40 with heavy loads, but loaded very long (longer than would feed in Glocks, etc), but felt uncomfortable because of the very high pressure signs. Switched back to Titegroup for peace of mind.
