Hello Richard,
Here is some information from Vittorio Bobba's swiss luger book, from pages 93-94 and 193.
This is in regards to the "U" shaped rear sight notch...
By the time the model 19006/29 W+F Bern came out, the U notch was the standard for that entire model run.
Regards.
Pete... <img border="0" alt="[typing]" title="" src="graemlins/yltype.gif" />