Hi Vance,
I doubt that Cast Performance would give you that guarantee and it probably would be meaningless anyhow. It seems to me that all of the forces acting on the bullet until it leaves the muzzle would be trying to keep the gas check slammed up against the base of the bullet. I would not be surprised if there was a separation after that time. Look at it this way, if you are close enough and the bullet does not dispatch the critter maybe the gas check would finish the job. At the very least maybe it would buy you more time for a follow-up shot. Seriously though bottom line is that you must do what your gut tells you. On a more serious note you might look at the .44 bullets at Midway specifically the customer comments. I was looking earlier today. You might check out the Hornady 265 grain interlocks. Lots of good comments about those. They shoot great out of my .444 Contender.