That cased magnum has something quite fundamentally wrong going on.
The stem is laterally offset. Meaning no longer coaxially aligned with the shank.
Zero chance the offset is how the pipe was originally made, which says botched repair of some kind. (The large portion of missing nomenclature wasn't buffed off, it was sanded off... The result of an after-the-fact attempt to minimize the wonky axial alignment.)
Weird because the stems and shanks of magnums are large and robust by definition, and a 5/8" or 11/16" diameter tenon is exponentially stronger than a typical-sized 3/8"(ish) one. You could use it as a crowbar.
The only thing that comes to mind is a known issue with some Dunhill magnums from that period is the cutter who supplied the jumbo blocks (apparently) got greedy and trimmed them LESS than he should have, leaving some weak, crack-prone wood behind at the shank end of the block. I've repaired several of them over the years and seen it first hand.
Here's footage from the OR for you shop geeks to show the sort of measures required to save them:
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Because it's a nightmare scenario, someone having botched a repair attempt years ago would be more likely than not.
All that assumes the pipe is a member of the "weak shank club", of course. Maybe the problem is/was something else. But nothing else comes to mind.