early 50's is my guess. I just happened to see something similar at the Glastonbury antique show this morning but it was chrome plated and manual wind with "militar" on the dial. the owner said it was late 40's so i'm thinking with the bumper yours might be a bit newer?
Serial number chart for Tissot: Based on this blow-up of the serial number, I’d say 1945-47: Looks like 1.6M or 1.8M number. gatorcpa