A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Paul Brewer
Date: 2017 Jun 16, 05:38 -0700
I think David is asking if all IX BM models are "modified" IX A's. I have quite a few BM's myself in all sorts of state. However, all mine have the IX A and the reference numbers altered from A to BM and the reference to match. Some are milled out some are just painted over with black to obliterate the A and a hand painted BM marked on top.
Technically, changing the Automatic attachment is the same as replacing an A's and it is a simple matter to remove the original eye piece and fit the double version.
I believe there were hundreds of new, unissued IX A's lying in stores and the factories at the end of the war and someone made a sensible decision to modify them to BM specification. Those at the factory were probably the milled out ones and the hand painted samples were probably done at station or even MU level.