I had an inquiry about this maker several weeks ago and have been trying to reconstruct some of my shotgun records that I removed from my computer.
If I remember correctly he worked for E. Thomas Junior in Chicago, I believe there's a shotgun with both their names on it and I have seen shotguns with just the Simon name on them and Chicago.
By, 1900 he is in Santa Rosa California.
If and when I can dig out more I'll post it.
1900 United States Federal Census about Joseph J Simon
Name: Joseph J Simon
Age: 49
Birth Date: Jun 1850
Birthplace: Austria
Home in 1900: Santa Rosa, Sonoma, California
Race: White
Gender: Male
Immigration Year: 1872
Relation to Head of House: Head
Marital Status: Married
Spouse's Name: Mary A Simon
Marriage Year: 1876
Years Married: 24
Father's Birthplace: Austria
Mother's Birthplace: Austria
Occupation: Gunsmith
Household Members:
Name Age
Joseph J Simon 49
Mary A Simon 43
Emma F Simon 22
Joseph F Simon 21
Mary Simon 19
Edward C Simon 16
Elizabeth H Simon 14
Gladys T Simon 9/12