Sorry fellas, I've been away and had no idea this thread was going . gas_gunner, no the original o-ring was is crumbs the first time I took it down for maintenance.
I currently have an o-ring in it that works although I doubt it will hold up to very many rounds. It is too thick (the thinnest I could get locally) but undersized on the diameter, so it thins out as it is stretched in place.
When time permits, I plan to take the whole shotgun to a store in San Antonio, and hopefully buy the correct one there. They have gunsmiths on site, and I'm sure they will let me put it in to verify that it's actually the right one.
Thanks to everyone for the suggestions and offers of help.