No such thing as a pre mark 1, they made standards and mki at the same time, mki just have the adjustable target rear sites...thats the difference and a few different barrel options than the standards. Standards have fixed rear sites. I have two standards, both from the late 70s, I also have a mki from the same time period.
The MK1 target wasn’t introduced until 1950. Adjustable sights and 6.875” barrel. So if one wanted to call a 1949 model a pre MK1 it wouldn’t be out of line. But only that one year.
