Denting a shotgun barrel is possible anyplace along it's length, not only at the muzzle. Your measurements would not concern me, too much. I'd be as careful as prudence allows, without being paranoid about it but, I'd certainly use it and enjoy it.
I'd love to see some pics of a Turnbull restored DHE. I hunt with a DHE, too, and as I recall the MWT are no more than that either. I'll have to look them up in my info and see.
Best, SRH
I would love to share some but, I can not figure out how to attach a photo on this site.
