This may be a Canadian pen?
Date code - .10

That one looks a wee ratty (worn/domed) but these often do crop up on later style Canadian Vacs, usually post-1942. Sometimes painted. Pain in hiney to remove. I'm inclined to believe some pens were originally so fitted

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mmm... I think it's aftermarket. the arrow head looks kind of funny too, maybe I'm seeing it wrong because of the angle, but it draws my attention.

Oh, the set is real.

I posted this a few days ago ..




The "domed" jewel unscrews, so I know it is threaded and that it can be changed if I so desire.