Thanks For the thoughtful,experienced input CC HUnter,but if you look close you can see both the front (brass)site,and the threaded "action",end...this piece was not "sawed",off
I thought I had a better picture of the threaded (breech)end but do not seem to I can provide one if need be (you can see the flash hole)
I had noticed what appeared to be a sight on the gun barrel, yet the features you described, as having a threaded end, for screwing into the gun breach, escaped my attention. The screw-barrel pistols were quite popular in the late 18th century and first half of the 19th century. There would be an octagon shape, or some other locking means of attaching a wrench, on the threaded end of the barrel. Also, considering the gun frame is missing, and with the massive blow-out in the barrel, it is doubtful enough force was expended to the rear, to blow the threaded breach and frame apart, I will venture that the barrel may have been removed before the burst occurred (The barrel wrenches for those pistols, would fit tightly, completely encircling the barrel, therefore, how could one fit a wrench over a blown barrel, for removal?). Very likely this was actually a "pipe bomb" charge, considering the various scenarios.
Very well may have been CC,your noted reasons a long with Bosn's tests,may support that as well.It appears this was the style that was Muzzle loaded (noting what I presume would be a ramrod guide?)and the barrel was unscrewed after or before the explosion?Not find any part of the rest of the weapon is a big clue as well.Thanks again!!