Okay, just something to look at when sizing long rifle bullets: how deep they go in the die will directly effect the diameter, especially with LBT designs, because the area you are having trouble with on the bullet is cut even larger than .371 by Veral and the smallest diameter of the sizing die is at the very bottom.

Nose first, with a GC.
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Knurled lock and liftout plug set before sizing.
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How deep it will travel into the die. Note the liftout plug(black) and the die pin, when the nose first bullet fully enters the die.
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Side view:
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