577-450 octagon barrel?

I recently purchases a tapered octagon 577-450 barrel. It is in poor condition with no makers name but there is a T and the serial number 1046 stamped under the barrel. There is a welded-on loop for a sling swivel on the midpoint ands a square stud 6 inches from the breech for a mounting screw that would come up thru the stock. It has a ladder rear sight and a blade front sight and the rear has the standard snider/enfield 1-14 thread and the notches that appear to be for a U shaped Peabody Martini extractor. overall length is 28 inches including the threads, 3/4 inch at the muzzle and just a hair over 1 inch at the breech end.

Anybody have any idea what this may have come off? I have never seen anything like it in my travels.

Tried to attach a photo, but the program ain't co-operating with this Neanderthal.
Appreciate any help,
Dave