Hi Limpitmine, I have the following 1950 LongBranch C No4 MK1* 91L8478, purchased new never fired, from Marstar back in the day.
Another I have originally savage no date No4 mk1* OC42361 oil black finish,
The last been worked on by everyone oiled black original finish, with the following numbers AT 17587, n 194? either a 3or a 3 stamped over a 1.
Is marked as a No4 mk1. hope this helps.
Regards Ian