Originally Posted by
garandsrus
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The other possible option is that your core seating punch isn’t the correct diameter, preventing the core from seating properly and expanding the jacket. The correct punch diameter depends on the jacket thickness and how deeply the core is seated, since the jacket is tapered on the inside. Different core weights will take different punches since the top of the core ends up at a different distance from the jacket mouth. If the punch is correct, the seated core will be flat on the top with no lead flashing that gets past the end of the punch. The brass will also not have a bulge from the seating punch.
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