Quote Originally Posted by thermaler View Post
I have pretty much all these bullets at my disposal--I was just wondering how much credence there was to the internal fragmentation/massive destruction theory--sounds pretty solid to me from what I gather here. Funny how I haven't heard many people step up and say anything nice about Barnes copper bullets which are supposedly known for their very significant mushrooming and very high weight retention.
The key to reliably bringing an animal down in short order (<~10sec) is opening the large arteries near the heart or the heart itself. The thing doing the slice does not have to be a massive lance. One can look at hunting arrows used over the last 7,000 years and see that. In fact there was a paper published in a refereed archeology journal with those conclusions.

These primitive archers took the time needed to make good broadside shots. In the case of American Indians, they even waited until the buffalo had started to step forward so the ribs would separate enough to give the arrow a better chance to enter the thorax.

With rifles, one doesn't need much bullet to get through the rib cage and yes, the more fragments one gets inside the thorax, the better the chances of causing the animal to quickly faint by cutting enough blood vessels to cause massive loss of blood pressure, . When they work, these explosively fragmenting projectiles work very well. These bullets, however, don't always get into the vitals when the shots are taken at quartering angles and through large bones.

The lead-free expanding bullets do so well by expanding modestly in the first few inches and then keeping their weight and shape for the rest of the penetration even when going through bone. A key factor, and not one that is well-understood, is that the copper alloys used are far more ductile than lead and the strength can be controlled through modern metallurgy. This is why they tend to routinely make beautiful mushroom shapes.

You can read more about wound channels, bullet weights, construction, and killing power in this note: Ideal Bullet Weight. One of the conclusions to be drawn is that the lead-free expanding bullets seem to show about the same killing power as a bullet of classic design weighing half-again or more as much. That is one of the reasons they are becoming more popular.