Mike when you're right, you're right, Bill's book is sometimes hard to reference and I obviously combined the wrong two pages. Oh well, Let me wipe the egg off my face and when i get a little more time I will set down again and hopefully get it right. I also didn't see that letter in front of the serial number, that is where my error really was plus a moment of dumbs. But just to start, the Letter E was first used in 1910 in the hammer 22. I'll research it more later and try to come up with a definite year. ADDED: Really miss Bill Goforth and his expertise on Iver Johnson's. He could look at a Iver Johnson revolver and tell you it's history and the name of the foreman who was on shift that day. He also would share his knowledge freely. Before if a misprint was found in his book he would quickly put out the correct information and would follow up to ensure you received it. Well, as every one knows, that finial appointment can not be rescheduled.
Try this again, 3rd model Safety hammer in .22, serial number E3533 was manufactured in 1927, 900 made that year. Sorry about the previous mistake, I looked at that E and the first time it appeared as an square, just one of those funny marking you will find on frames. The second time it I could see that it was a E.