With the truncated cone nose of the bullet inside the case, I would worry about gas cutting in the barrel - that would divert propelling gasses to the edges of the bullet rather than the base. It would lessen obturation (expansion of the bullet to seal the gas pressure) and focus the hot gasses to the edges of the bullet. Over time, the rifling erosion could be significant and affect accuracy.

John

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- Cogito, ergo armatus sum -