Range Report Sectional Density

[damoncali]

I'm working on building an online database of bullet ballistics data, and wanted to get a little feedback from folks.

Do you use sectional density for anything at all? I'm told hunters care about it, but I don't hunt much (at all, really), so I'm a little out of my league there. Anyone have a legitimate use for that data?

Thank in advance.

 

[RobertB]

Yes, people use it. If I was wanting to be the top dog in info I would think it was important.

 

[LastShot300]

Most people I know don't know what SD is for. Among other things too many myths regarding its use. Since the computer will do the work...why not?

 

[damoncali]

It's easy enough to calculate, I just don't know why someone would want it. If I knew, I could put it in the right context.

 

[Smooth73]

It's used in calculating the ballistic coefficient of a given projectile. If someone was making their own bullets, you would want that information to calculate your BC, so you can get accurate external ballistics. Wiki has the formula.

 

[bowslngr]

There are rules of thumb for different classes of game species that require a minimum sectional density. More sectional density equates to better penetration, all other things being equal.

As a result, it is also useful in comparing the merits of one caliber vs. another for use on a given type of game when looking at the typical range of bullet weights in each caliber.

Here is some info from a Chuck Hawks ariticle:

Understanding this concept has cleared up a lot of confusion (for me) about bullets and has provided the means by which I can more easily compare bullets and cartridges. A SD of .180 would be acceptable for hunting varmints. A SD of .230 would be good for hunting CXP2 game such as deer. A SD of .280 would be appropriate for hunting CXP3 game such as elk. And, a bullet with an extreme SD of .330 would be chosen primarily for heavy, thick skinned CXP4 game such as elephant.

 

[Bob 964]

What is important is the ratio of sectional density to G7 BC. Dividing the sectional density by the G7 BC gives you the "form factor" of a bullet. The form factor is a measure of a bullet's drag, as compared to the drag of the standard G7 projectile. Form factors greater than 1.0 are bad. Form factors less than 1.0 are good. The lower the form factor, the less drag the bullet has and the more efficiently it flies.

Bryan Litz had a good article on this subject. I think it was in a May 2011 Berger Bulletin. Here is the link, if you are interested.

http://02b0516.netsolhost.com/blog1/...analysis-tool/

 

[damoncali]

What I'm looking for is a good reason to have sectional density listed along side bc and form factor. Sounds like the only application is hunting? Seems dubious considering differences in bullet designs, but I admittedly know almost nothing of terminal ballistics.

 

[roggom]

Its all about penetration, wether it be hunting or a car door, or cinder blocks. It is an important variable to have the "big" picture. Lack of SD is the reason some guys cant understand the difference between a 300blk shooting 125 gn ballistic tips vs a 6.5 grendel and the same bullet. Even if they are leaving the muzzle at the same velocity.

If you are building an online database and you want traffic, it would be a good idea. Just do some google searches for any bullet + SD and you will find that MidwayUsa has SD listed and sits on top of the google search.