No idea if this would work, but maybe get a length of a thin, strong, rigid wire, bend one end up so it will bite into the snake, and feed the other end (sharpened if necessary) up through the barrel from the chamber through the snake, and use the wire to pull it out. Coathanger wire might (emphasis on might) work. You'd need to make sure that it was soft enough to not scratch your barrel
Or maybe you could use the wire like a big needle and attach a thin cord or line thats knotted in a few places and try to use the wire to feed the cord through the length of the snake so you can get a grip on cord at the muzzle end.
Problem with both these, though, is that they might only apply pressure from the base of the snake, so not sure if that would be helpful.
And I'd try the hemostats first.
On a related note, I've been thinking of running some strong fishing line through the cords of my bore snakes to reinforce them to help prevent something like this from happening.