I see why there appears to be an angled inward look to the opening of the U cut-outs, but Id like to suggest looking at some other angles....
....in some of the upright photos, the inward angling is far less pronounced and we might be seeing a combination of wear and tear, paint loss etc, odd lighting etc to account for some of this inward angle.
....
but these would have been made before the age of CNC....so if machined, punched etc by machines that were not perfect (nor run by a human that was not perfect) this may account for some imperfect details as you rotate the piece.
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I tried pointing out a few thoughts here:
Note the slightly sunken band "line" at the base of the cone. It appears as though the cone rises up a hair at its base and proceeds outward/upward from there.
Note some of fluted lines are different lengths: wear/tear or imperfect machining?
Note that the back opening with the U shaped cut outs is very thin.