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167
06-26-09, 00:58
Is there an accurate way to measure the actual crush area of an expanded HP? I thought I had read that there was a method for that on the firearms tactical website but I spent a couple hours digging around and I couldn't find it so maybe I was mistaken. I ran a search here and couldn't find what I was looking for either. I know the standard method for measuring the recovered diameter of a round is to the measure the bullet at its greatest and least expansion and then average the two but it would seem that on some bullets they end up with a rather rounded, almost ball shaped profile that this method wouldn't accuratly measure the actual crush area because it would be more inclined to just push tissue aside. Even though I know at some point during the expansion they are not in that condition, I would think that these rounds would be less effective than a round that didn't have as much a ball shaped profile. Right? Or is that logic off base?

167
06-26-09, 11:35
I had already read that, I didn't feel as though it answered my question. It shows how to calculate the recovered diameter of the bullet, not necessarily the crush area of the bullet. I would assume, that depending on bullet profile, the crush area and recovered diameter may not be the same. At what point do the folded back petals of a HP stop crushing tissue? Or is there no difference between the RD and the actual crush area of a HP even though some HP's seem to end up with a profile that would not be conducive to crushing tissue. Basicly I am wondering if my logic is completely wrong or half way correct. I doubt I am completely right because I never am:D Thanks.

The comment at the bottom of the provided link is basicly what I am getting at. How do we quatify and "sharper leading edge"?

Shawn Dodson
06-26-09, 12:25
The "crush area" (effective diameter) is dynamic and varies with bullet velocity and tissue elasticity.

At the beginning of the wound track the bullet crushes the majority of elastic soft tissues it comes in direct contact with. The bullet is moving faster than the soft tissue can stretch out of its path.

Near the end of the wound track the majority of elastic soft tissues stretch around the passing bullet.

Thus the permanant cavity narrows from beginning to end. It is not a constant diameter.

A penetating bullet usually pulpifies nonelastic soft tissues that come into direct contact. (Nonelastic soft tissues may also rupture and fissure.)

I hope this helps.

167
06-26-09, 12:34
Yup, that is more of what I am looking for. So there is no real way to figure out the actual crush area of a bullet because it varies with velocity and what type of tissue it contacts, right? So in other words, there is no accurate way to measure crush area? Theoretically though, would a flatter front profile of a bullet be more effective compared to a bullet of the same diameter that has folded back petals?

Shawn Dodson
06-27-09, 12:26
I forgot to include yaw.