Bumper from late 40’s early 50’s? It has the same layout as my 1944 model. My Calibre is 28.10A with a 163.617 reference. Can’t see the size. If this is indeed as large as suggested above it is a completely different thing. Searching in that area should give you some answers.
I believe it's the same watch you've posted in October '18 and '19. Or as someone wrote when last posted, a beast in the best sense.