made approx. 1917/1918
By model and serial number. Go to proofhouse.com
1912
1871
2006
1911
1910
probably WW1 era.................
1919
Just saw a site saying a serial number 88000 was manufactured in 1916. So it may give ya an idea.
No known sn data published.
Early 1930s
No published sn data I am aware of.