Will a shogun shell adapter work in a flare gun?

I know that if you use a flare gun with a shotgun shell it will explode in your hand because the barrel is plastic but I was wondering what would happen if you used one of those steel shotgun shell adapters they use to adapt shells smaller than a 12 gauge to fit in a 12 gauge shotgun. Since the shell adapter is steel and design to be use in a shot gun would it reinforce a 12 gauge flaregun enough to use it as a handgun/shotgun?