Would be nice to handle them - all.

Both appeared to be made from Military parts.

The styling is all military. I've never seen such a butt plate extension before, except for the exaggerated Swiss match rifle butt plates with hooks for offhand shooting- later, mid to late 1800's.

A musket or fowler made from musket parts certainly does not need one and it would catch on clothing in anything but deliberate fire on a range. Being a musket (large bore smooth) sort of dispels that thought.

Many simple cheap guns were made for the 'colonial' trade - natives in India, Africa and South America.