Originally Posted by Shakethetrees
... reinforces at the muzzle and breech ...
It was precisely these rims that took to realize that this wasn't a breech chamber. All chambers that i happen to know (and those that i keep) don't have any protuberances in both back and front. Such features do not help at all the matching of the chamber with the breech cavity and barrel entrance ... specialy considering that, once the chamber is introduced in the breech, you have to push it into the barrel and, in some cases, rotate it.
Actually what is often seen is a significant tapering of the chamber mouth, to provide for a better sealing when you push into the barrel.
Although i found somehow problematic that the front of handle is placed so far and close to the mouth, nearly preventing the chamber introduction into the barrel.
The absence of a lip in the touch hole, although often seen in noise makers, doesn't exist in many other cases; probably because in such case a match fuse is used, instead of loose priming powder being poured.