Can someone give me a quick physics lesson on sectional density. I keep reading about how it may be the best indicator of a bullets killing power but I don't understand why.

The sectional density (weight/7000/dia squared) is a good representation of the relative length of the bullet. Since it's reasonable that varmint weight bullets are less, they will be shorter in a given calandar.

It's just one measure of killing power.

Today the bonded and particians are a much better selection than just sectional density.

A 7mm 175 grain bullet has a sectional density greater than a 300 grain
.375 H&H and it's not going to be a better killer.

There's far more than SD to decide on what bullet. Again, it's just one of many factors for choosing the best bullet.

Hi cgturner7,

Vapo summed it up fairly well. For a little more info go to the below site:

http://www.chuckhawks.com/sd.htm

When you finish the article....at the bottom of the page click on "Rifle Info" for an index with a varied amount of info. Hope this helps!

Dave

When all bullets were simple copper jackets and lead cores sectional density was much more important in determin ing bullet performance on game..Bullet construction is now however the most important factor as to how a bullet will perform on game.

Sectional density is basicly how much weight a bullet is delivering to a specific area.

A 150 grain .277 bullet has a higher sectional density than a 150 grain .308 bullet because it is transfering the same weight in a smaller area (circle).

This is just a simple way to look at it.

All things being equil, the bullet with the higher S.D. will penetrate deeper!! That doesn't mean it has more "killing" power, it just means it will drive deeper into the target.

The problem is, as stubblejumper said, these days all things are NOT equil!!! The construction of a bullet makes all the difference on how it transmits it's energy to the target, and that's usually described as "killing power".

Drilling Man