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Also, the BXR tip is a lot longer/deeper and so, compared to a ballistic-tip-type, it has a 48% impact area compared to that of 22%; a semi-pointed bullet has less than 10% impact area to initiate the bullet expansion.
What this means is that the initial expansion of the bullet is started quicker and more uniformly, so the bullet's jacket starts to retreat and peel back, followed by the softer lead core to form the characteristic mushroom shape of a lead cored bullet. The tip is usually disintegrated or pushed within the front half of the bullet, expanding to twice its size to increase the surface area and thus wound channel to create large hydrostatic shock, and hence energy transfer. The rear section of the BXR remains intact to push the bullet forward and continue the penetration.