Huh....!
The Indian trade musket has a patent breech.
I can't remember about the Pedersoli Mortimer
The side by sides may have a tiny amount of countersink at the short flash channel but that's all.
I've not scraped nothing for decades now, nor poked at anything down in the breech, not after I realized I didn't need to using hot water..
What I do know is that an awful lot of folk are put off using muzzleloading guns because they are .....very scared of the cleaning processes based on what they read here and other places!
To them pilgrims it's like they are going to end up with a corrosion demon haunting them for eternity!
It's not the boogy man's gonna get ya any more, it's flash, ol' flash rust, BOOO! Bet ya jumped.....