Don't know about on people as all of my experience has been on game animals, mostly deer. There is a big difference in the stopping power, not in the weight of the bullet, but in it's construction. What has always worked best for me is a copper jacketed hollow point. You want the bullet to enter, penatrate to the vital organs and then just sort of explode. The copper jacket keeps the bullet together long enough to reach the vital areas and the hollow point causes the bullet to expand and in most cases actually splinter into several different fragements.
I tried using solid steel jacket and copper without the hollow point and it caused a lot of problems. More often than not the bullet did not do enough damage to bring the animal down fast. Ended up having to track them for miles. When cutting the deer up the full jacketed rounds were still intact. Whereas with the hollow points, most of the time it is a clean kill, where the deer is dead by the time I got to them. Also the bullet had mushroomed to about twice its normal diameter with several fragments going off into different directions.
I'm not an expert by any means. This is just from my experience and that of fellow hunters.
Hope this helps.
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Richard
The debate is not about guns,
but rather who has the ultimate power to rule,
the People or Government.
RKBA!