with holed lug in downward position to pin barrel in place , the barrel burst to the left , opposite most touch hole sides.
The breech likely was tanged and secured at it's rear.
Evidence of a threaded breech plug is thin. But lines can be seen hinting a thin threading existed(?) Hard telling from the picture.
Flint or percussion? Can't tell really though pins can hint of older builds. Not always though.
IF the breech plug was threaded thin it could have given way. Or it could have gotten corroded through neglect or a foul weather event ?
I'm not seeing a match to the barrel in a quick search . And not knowing model/builder or ignition type it's a guess as to what the breech might have looked like.
Again , likely secured with a lug to the rear of the breech.
Pics I'm seeing are short looking plug potentials.
(The threaded inside part can't go past the hole you ignite the powder through.)
The rear of the breechplug might have remained attached to the stock when the barrel failed and blew out to the left.
If this picture survives the holed rear of plug has a fastener in it.
