@ 1830's to late 1850's
Your weapon is not a flintlock but a percussion cap shotgun rifle made by GG Julcher of Philadelphia PA from c 1840 to the Civil War. It is an unusual weapon as the shotgun lock (Hammer and cap) on the left side is upside down, an extremely clumsy solution as the cap tends to fall off.
Depends on what gauge, type of use (hunt, compete, home defense), etc.
I was offered $500.00 for mine.
The Ithaca brand shotgun was manufactured in New York. I don't know if this is the one you were looking for.
2011
This Shotgun was manufactured by the Mossberg Company.
Unknown.
Mossberg
Unknown.
No
Your Winchester shotgun was manufactured in 1914.
Manufactured by Davenport. sales@countrygunsmith.net