Jim,on butts and briskets,190-205* is the target temp,but you want to go until it's tender. I know it sounds strange,but sometimes they are tender at 180*,sometimes higher. When a thermometer probe or fork goes in very easily,it's done and need to rest.
Turkeys,and chicken,need to go to at least 165*. Anything lower and you risk not killing all the nasty stuff that can make you sick. I hope this helps.