Does "anyone" ever take Sectional Density into consideration!!

[Alibiiv]

I've been reading LRH forum for a number of years now. I read the various forums/postings and it seems like the "only comparable variables" are muzzle velocity and the only other, holy grail measure of performance, "ballistic coefficient"; BC of a particular bullet are being interjected when making caliber performance comparisons. While reading the various postings, sometimes I will interject, "How about sectional?" when one makes a comparison when arguing/discussing particular calibers. It's almost like the post never hit the posting or it was deleted before it hit the post! Is the sectional density of a particular bullet something that is not worth putting into the equation when discussing and comparing ballistics and whether the 6.5 Creedmore is better than the 50BMG when shooting an elk and 800 yards!!???? Am I missing something here? Could I get some help in understanding why sectional density is not being put into the equation as much as ballistic coefficient and muzzle velocity; or, do I need to buy new glasses????

 

[Mikecr]

Could I get some help in understanding why sectional density is not being put into the equation as much as ballistic coefficient and muzzle velocity?

Sectional Density is part of BC.
BC = SD/FF (bullet's sectional density to its coefficient of form).
That's EXTERNAL ballistics.
None of this means anything w/regard to TERMINAL ballistics.

 

[Milepost]

Sectional density used to be a big thing years ago before the advent of long range hunting. Now any of the long high BC bullets have a high SD too as both go hand in hand with the length. The design parameters for any bullet are dictated for it's use whether it's for hunting or target. The SD is a by-product of the design. By design an African Big Five bullet will have a high SD and a small lightweight varmint bullet will be small one.

 

[elkaholic]

I would qualify a little some of the responses by saying that, yes higher b.c. also means higher s.d. This is a long range forum, so naturally, high b.c. are normally the bullets of choice. Having said that, a 150 grain round nose .264 has the same b.c. as a 150 with a 27s ogive! I think what you are saying is that sectional density DOES matter, and in fact matters on lower b.c. bullets for some applications. I like high b.c. as much as anyone but I posted a thread several years ago called "b.c. crazy"! My point was essentially people over look better bullet choices than the highest b.c. when they very likely never shoot over 500 yards, if even that far.
Infact, I suspect that's true of an awful lot of people on this forum these days.

 

[hunter67wa]

Higher SD will help with more penetration. It has more ***. lol I shoot a 155 Lapua Mega in a 6.5x55 that will go stem to stern on animals.

 

[memtb]

Always!!! As mentioned, a high BC , generally relates to a higher sectional density. What many people, especially the "long range crowd", seem to disregard....it the bullet weight shed after impact, by many of the long range bullets, will greatly affect penetration! Thanks, but for a hunting bullet, I'll sacrifice a little BC....for a much better bullet designed for weight retention! memtb

 

[mjkten]

A round ball would have very low sectional density, while that same material shaped into a cylinder would have a much higher sectional density. Put an aerodynamic point on it and a shapely boattail rear end, and your BC is optimized. Sectional density usually is thought of in terms of penetration I think.

 

[Capt RB]

Most high bc bullets have static sd that are very high. He in lies the issue. Once they come in contact with game many high bc hunting bullets shed their energy and disrupt their shape changing their SD dramatically. This is seen in close range shots where they may not do the job. A mono though of high bc will have a lower bc in like shaped bullets but maintain their sd due to not drastically changing shape and losing the petals keeping the shank like a partition style. Long round nose bullets have excellent hunting properties at closer range with exceptional SD and a wide exposed lead tip for excellent expansion characteristics. The just don't fly well. They can be quite accurate though. My 760 pump gun has shot 180 round nose corelocks into single hole groups often enough to prove it isn't a lucky group.

 

[Edd]

Knowing sectional density of a bullet has very little value. It is determined by the diameter/caliber and the weight of the bullet. It gives no consideration to the shape or construction.

All bullets of a caliber that weigh the same will have the same SD regardless of their shape.

 

[mjkten]

I think we all know what weight bullet for a given caliber is suitable for large or medium game, this is partly contstruction of the bullet, and partly weight, which for a caliber, goes hand in hand with SD. We don't think about it in terms of SD, but choosing a heavier bullet means you're gaining SD...just my take on it.

 

[FURMAN]

You are kidding right? Sectional density is weight divided by diameter. A 220 grain 30 cal bullet will have an sd of .331. Ballistic coefficient is a coefficient used to calculate a bullets resistance to slowing down in air. One of the 220 Woodleighs has a bc of .359. The 220 ELD has a bc of 650. Sectional density is an important consideration but is accounted for in bc. BC is what is really important when determining external ballistics for long range hunting. Terminal performance is a completely different subject.

 

[Alibiiv]

I would qualify a little some of the responses by saying that, yes higher b.c. also means higher s.d. This is a long range forum, so naturally, high b.c. are normally the bullets of choice. Having said that, a 150 grain round nose .264 has the same b.c. as a 150 with a 27s ogive! I think what you are saying is that sectional density DOES matter, and in fact matters on lower b.c. bullets for some applications. I like high b.c. as much as anyone but I posted a thread several years ago called "b.c. crazy"! My point was essentially people over look better bullet choices than the highest b.c. when they very likely never shoot over 500 yards, if even that far.
Infact, I suspect that's true of an awful lot of people on this forum these days.

"My point was essentially people over look better bullet choices than the highest b.c. when they very likely never shoot over 500 yards, if even that far" Rich my point in case. Is seems like there is a whole lot said about BC, but really nothing said or compared to SD. I suspect that as you have written in this post, because a higher BC equals a higher SD. It just seems to me that it ought to not be a complete given.Postings will have that their particular caliber and muzzle velocity did such and such carnage and tissue damage, but it seems like SD is totally left out of the equation when making comparisons. And....I believe that to make a better comparison of a particular caliber/cartidge's abilities to bring game down that comparison ought to be part of that comparison. I'd also like to state that I know this is a LRH forum, however not all of us are shooting from one mountain to or mountain range to another, some of us readers actually consider 300 yards a long poke! I hope that I am making sense here???

 

[Alibiiv]

"My point was essentially people over look better bullet choices than the highest b.c. when they very likely never shoot over 500 yards, if even that far" Rich my point in case. Is seems like there is a whole lot said about BC, but really nothing said or compared to SD. I suspect that as you have written in this post, because a higher BC equals a higher SD. It just seems to me that it ought to not be a complete given.Postings will have that their particular caliber and muzzle velocity did such and such carnage and tissue damage, but it seems like SD is totally left out of the equation when making comparisons. And....I believe that to make a better comparison of a particular caliber/cartidge's abilities to bring game down that comparison ought to be part of that comparison. I'd also like to state that I know this is a LRH forum, however not all of us are shooting from one mountain to or mountain range to another, some of us readers actually consider 300 yards a long poke! I hope that I am making sense here???

 

[FURMAN]

I think your question may have more value at 100 yards but this is a long range hunting forum. Provided the bullet is capable of good terminal performance bc rules. I suspect this thread will turn into another giant argument just like the 26 Nosler vs 300WM.

When I am building a rifle or buying one for that matter. I first consider the game I will take with it. I then consider the weight of bullet I intend to shoot then I consider how fast I want to drive it then I pick my cartridge. The overriding pieces of those decisions is energy/momentum at the max distance I intend to shoot, the BC, and necassary muzzle velocity to make it happen.