If you are using a heavy-ish for caliber bullet at a moderate speed, I think Sierra GK bullets are great for deer. It's when they are used up close and cranked up near 3,000fps or are lightweights with low SD that things get dicey with them coming apart. Not much different than other cup/cores like Powerpoints, Speer BT, Core-Lokt, etc. Cup/cores like this are great killers in the 7mm-08 and .308 and often exit.
