Sectional Density - Desert Dog

[DaddyFlip]

It’s too late to be thinking this hard. LOL Maybe the advent of the monometal bullet has changed the importance of at least BC? They’re longer for the same weight vs a bonded bullet, so a higher SD. But as you pointed out, caliber size (frontal mass) is a big factor too.

Try thinking this hard after a fifth of whisky! All I'm saying is that for some reason, SD has gotten a lot of airtime in the hunting world recently and I don't believe it is warranted IN THE WAY IT IS HERALDED. There was a post here not long ago someone said (I'm paraphrasing), "I chose the 7mm (whatever) over the 30cal (whatever) for it's higher sectional density." There's nothing wrong with any 7mm in a typical hunting situation, but no 7mm is going to knock 'em deader than any equivalent 30cal in the hunting situation the poster was talking about. Poster was merely comparing a mathematical figure in a loading manual between bullets of equal mass (I know because I recall the context).

 

[Killingtime]

Terminal ascent is one of, if not the best performing hunting bullets available that happens to have a decent bc.

it’s a great bullet if your doing longer range hunting but it does nothing inside of practical hunting distances. Better than older designs. I’ve shot literal thousands of rounds from 500-1700 yards and most people can’t consistently hit a pie plate ate 400 yards. so for most people I do not believe these bullets really matter but if you have the ability and like to hunt at longer ranges they are nice to have.

 

[DaddyFlip]

Apparently, the Terminal Ascent bullet evolved from the Trophy Bonded Bear Claw:

Do you think that the TA is better than the TBBC in a heavy game or DG situation? Maybe the TBBC resembles too much two other bullets that outsell/outclass it (like maybe the Barnes TSX and the Swift A-Frame?). To me, the TA is nothing like the TBBC; not even comparable. It's more like a CX or a BT. Assuming it is the "best hunting bullet" they've ever made, I'm willing to wager it's cheaper to make than the TBBC, which is the driving force behind the majority of innovation these days.

 

[Tradmark]

not sure which traditional bullet will punch through both shoulders of an eland at 150 yds out of a 6.5 creedmore like the terminal ascent but if you have one let me know about it.

 

[Killingtime]

not sure which traditional bullet will punch through both shoulders of an eland at 150 yds out of a 6.5 creedmore like the terminal ascent but if you have one let me know about it.

I would not shoot a eland with a creedmore but a 22 year old Barnes tsx would have done it I suppose

 

[Killingtime]

And the old barne x bullet from the late 80’s probably also

 

[DaddyFlip]

not sure which traditional bullet will punch through both shoulders of an eland at 150 yds out of a 6.5 creedmore like the terminal ascent but if you have one let me know about it.

I'm looking at my list of available 6.5 cartridges and I don't see any I personally would consider 'traditional'. No dogging on the caliber; I wager there are very few traditional 6.5 bullets to consider. Or maybe if I include the 257 WBY the old Partition or Ballistic Tip could do it? I'm guessing. I don't know anything about the TA bullet; I'm just saying it's not in the same class/use case as the TBBC. (I think I'm right saying this?)

 

[Killingtime]

I'm looking at my list of available 6.5 cartridges and I don't see any I personally would consider 'traditional'. No dogging on the caliber; I wager there are very few traditional 6.5 bullets to consider. Or maybe if I include the 257 WBY the old Partition or Ballistic Tip could do it? I'm guessing. I don't know anything about the TA bullet; I'm just saying it's not in the same class/use case as the TBBC. (I think I'm right saying this?)

they market the TA as the evolution of the TBT which was marketed as the evolution of the TBBC. But the tbbc was made because of failure from the partition I believe on a buffalo. And to me the TA is a high bc long range hunting bullet. Like you said two different markets.

 

[CoElkHunter]

Do you think that the TA is better than the TBBC in a heavy game or DG situation? Maybe the TBBC resembles too much two other bullets that outsell/outclass it (like maybe the Barnes TSX and the Swift A-Frame?). To me, the TA is nothing like the TBBC; not even comparable. It's more like a CX or a BT. Assuming it is the "best hunting bullet" they've ever made, I'm willing to wager it's cheaper to make than the TBBC, which is the driving force behind the majority of innovation these days.

I personally wouldn’t use the TA on DG if I ever had the opportunity to hunt DG. Are the TA even loaded in .375 and up weights? My DG rifle cartridge bullets are Barnes TSXs by default because TBBCs and A Frames are mostly MIA. I have no way to personally “test” each of them so I rely on the real world results from the many DG hunters here on AH. Seems Barnes TSX work well. But Federal obviously is pushing the TA and Hornady their own proprietary bullets and cartridges for the newer generation of longer range shooters/hunters. To each their own but I enjoy the way I hunt at MY own pace and distances.

 

[DaddyFlip]

I am a big believer in heavy-for-caliber bullets. As long as velocity is still adequate.
Such as:
173Gr for 7x57mm Mauser
220Gr for .30-06 Springfield, .300 Holland & Holland Magnum, .300 Winchester Magnum
250Gr for .338 Winchester Magnum
286Gr for 9.3x62mm Mauser
400Gr for .404 Jeffery
550Gr for .450 Rigby Magnum
600Gr for .505 Gibbs

I somehow missed @Hunter-Habib reply on Page 1; he makes a good point, as did everyone else on Page 1 (who, in my opinion, took a soft stance WITH Desert Dog that SD isn't a top bullet criteria). Notice that as @Hunter-Habib increased bullet caliber in his preferences, he also increased bullet mass- for very practical reasons. Let's look at the resulting SDs:

7mm 0.325
308 0.331
338 0.313
9.3mm 0.305
404 0.319
450 0.375
505 0.338

SD has nothing to do with velocity or bullet construction or terminal performance on game. It's still up to the hunter to choose the correct caliber, weight, and velocity for the intended task and SD is merely a mathematical description of mass vs. diameter. Using @Hunter-Habib typical calibers and weights, who would choose a 7mm or 308 over a 404 for either plains or dangerous game strictly on the basis of SD?

 

[Tradmark]

Same basic construction. Just a little more aerodynamic and the grooves are just slighly more aerodynamic. Not sure what design difference makes it inappropriate for what the tbbc was used for other than it is just also better for longer distance hunting. It is a tough bullet and one can see how it compared watching the mason leather channel on youtube or do what we do and try em. There is nothing but plenty of traditional bullets in 6.5. Any of the round nose for the swede, coreloks, game kings, game changers, hornady interbonds, ballistic tips, partitions, winchester poer points, the federal cup and core, speers. Me and my kiddos have killed every african plains game animal and elk that we have shot at with one shot and not needed a follow up. Point is i wouldnt attempt it with a 6.5cr with any of the above bullets i listed nor any of the other bullets listed hunting bullets but are crap hunting target bullets though i have watched the dumpster fire ensue when others did. And yes, that bullet works even better out of a 30.06 or a 300wm

 

[Hunter-Habib]

I somehow missed @Hunter-Habib reply on Page 1; he makes a good point, as did everyone else on Page 1 (who, in my opinion, took a soft stance WITH Desert Dog that SD isn't a top bullet criteria). Notice that as @Hunter-Habib increased bullet caliber in his preferences, he also increased bullet mass- for very practical reasons. Let's look at the resulting SDs:

7mm 0.325
308 0.331
338 0.313
9.3mm 0.305
404 0.319
450 0.375
505 0.338

SD has nothing to do with velocity or bullet construction or terminal performance on game. It's still up to the hunter to choose the correct caliber, weight, and velocity for the intended task and SD is merely a mathematical description of mass vs. diameter. Using @Hunter-Habib typical calibers and weights, who would choose a 7mm or 308 over a 404 for either plains or dangerous game strictly on the basis of SD?

@DaddyFlip

That is a very knowledgeable assessment of yours. I would also add that the 7mm or .308 bore calibers hold a flatter trajectory out to longer ranges than say... a .404 or larger dangerous game calibers. This is definitely an advantage for hunting African plains game.

In my experience, few African plains game shooting occurs at ranges under 100 yards (invariably around 150 to 200 yards being more common). African dangerous game shooting occurs seldom at ranges above 80 yards (with around 50 to 60 yards being more common). Some sportsmen in recent years have begun to do things differently, by taking (for example) Cape buffalo at ranges above even 300 yards. But this is not typically encouraged.

 

[Beck]

I don’t know if that particular cutting edge bullet would out penetrate a 500 gr Northfork (because I have no experience with either), but it goes to show what a useless measure sectional density is by itself. What is the sectional density after the bullet mushrooms? Maybe sectional density was a more valuable indicator when nearly all bullets were thinly jacketed lead core bullets with very similar designs. There’s a lot more variation in bullet designs today. It’s also a lot easier to share and find information on what works and doesn’t.

Are any of the metrics useful when they are looked at by themself? I don't think so

 

[Beck]

Sectional density matters more or did matter more before all the advanced bullet construction companies have developed. 458win was considered subpar from everything I’ve read decades ago but with modern solids it will pass through anything. The 150gr bullets for the 35rem from Winchester I believe were dropped back in the day because of poor penetration on whitetail. Now they make mono’s much lighter that will blow straight through them. I personally believe two things can be true at one time and modern propellants and modern bullets have changed the game for every caliber out there.

No doubt that modern bullet design has aided today's hunter.

 

[Mark A Ouellette]

Are any of the metrics useful when they are looked at by themself? I don't think so

Exactly! Sectional Density is meaningful when it is the only variable. All else being the same, a projectile of a higher SD should penetrate further. Comparing similar properties from different manufacturers one has to allow for unknowns such as different ogive configurations or meplats, jacket thickness, ease of expansion and a dozen other factors!

To gather significant data from controlled tests, only one variable change can be measured at at a time. Further, sample sets need to be 10 at a minimum, 50 preferably, and 100 or more to be truly significant. That’s a little hard for anyone short of a manufacturer to fund!

As shooters we can however gather data from shooting into wet phone books or gelatin, examining womb channels of animals we kill, or observing that bullet A renders dead right there results time after time.

Bullet technology has increased so much in my lifetime!

 

[Killingtime]

Same basic construction. Just a little more aerodynamic and the grooves are just slighly more aerodynamic. Not sure what design difference makes it inappropriate for what the tbbc was used for other than it is just also better for longer distance hunting. It is a tough bullet and one can see how it compared watching the mason leather channel on youtube or do what we do and try em. There is nothing but plenty of traditional bullets in 6.5. Any of the round nose for the swede, coreloks, game kings, game changers, hornady interbonds, ballistic tips, partitions, winchester poer points, the federal cup and core, speers. Me and my kiddos have killed every african plains game animal and elk that we have shot at with one shot and not needed a follow up. Point is i wouldnt attempt it with a 6.5cr with any of the above bullets i listed nor any of the other bullets listed hunting bullets but are crap hunting target bullets though i have watched the dumpster fire ensue when others did. And yes, that bullet works even better out of a 30.06 or a 300wm

I’ve loaded TA 200gr and 190gr ablr in a 30-06 and With the right propellant it really made it act a like a older 300wm (shooting 180-185gr) at distances past 500 and with the 130gr ttsx its so flat its like my weatherbys inside of 400yds. im able to load 260ablr in my 375 and feel real comfortable hitting 500yd and 600yd target id feel comfortable with that bullet on everything in NA and all PG but I’ll probably load the 270gr Barnes instead when I go to Africa incase I’m hunting because I don’t think that accubond would be good if I stumbled into a buffalo but the mono I believe would work just fine.

I’m rambling but the with modern bullet design and propellant I agree we have extended ranges on and made many cartridge and caliber perform better on game and at distance that previously would have been questionable. Also it has made many people think there bullets are better then they really are. Like you said trademark I’ve seen the dumpster fire aswell with guys I have shot PRS with go hunting using target bullets thinking they will perform well on a specific type of game.

 

[Wyatt Smith]

I think sectional density has more merit when comparing bullets of the same weight, from different calibers, like a 150 grain 270 bullet should put penetrate a 150 30 caliber bullet and a 200 grain 30 caliber should put penetrate a 200 grain 338 bullet.
Of course it should only be considered when bullet construction is similar. I don’t think anyone here would be surprised if a 150 grain TSX from a 30-06 out penetrates a 150 power point from a 270.

 

[CBeck]

Are any of the metrics useful when they are looked at by themself? I don't think so

Exactly this….The real answer to the SD debate:

Why consider SD?

Because it’s simply a quick way to compare bullet weight within the same caliber and design. Higher SD in that context just means heavier-for-caliber, which usually gives you a little more penetration margin.

But SD is only one piece of the picture.

Bullet construction, caliber (frontal area), and expansion/weight retention have a much bigger impact on real-world performance—especially on large or dangerous game.

Focusing on SD alone is like buying a used car and only checking the transmission…..The engine, electrical system, and body matter just as much.

SD isn’t useless…..it’s just not the whole story.

 

[Jefferry404]

fwiw:
for my reloading, i use Schwartz's analysis as a comparative tool for various bullets, so as far as math goes... I use various web stuff to setup my bullet table, so is somewhat based upon a figment of my reality
This shows what has been stated here. That as SD increases, expansion decreases and penetration increases. Simple fact is for a given bullet, to get lower SD, means lower weight and this allows for a higher max velocity (i used Hornady reload manual for max. velocity), means more expansion, means less penetration.

 

[DG870]

I think when you talk about BC and SD you have to discuss them separately by function. A bullets travel has two components, external ballistics or how it flies through the air and terminal ballistics or what happens when it hits the target.

Ballistic Coefficient (BC) is how easily it flies through the air so with today interest in long range target shooting and hunting, high BC bullets are the rage. Two bullets of the same weight starting at the same speed, the bullet with the higher BC will retain speed better so will have less drop, less wind drift so that’s a good thing, right.

For target shooters, the end result is a hole in a target or the ding of steel, but for hunters the job is not done.

Terminal Ballistics start with the bullets travel through the animal so the Sectional Density comes into play here. How the SD changes as the bullets goes through the animal is a big deal. Growing up I read about the 6.5x54MS used by Bell and Hemingway for elephant and lions. They used 156 to 160 grain bullets with high SD going maybe 2400 or 2500 fps. They talked about the deep penetration they got from these bullets. The low impact speed even with softer bullets allowed the bullet to maintain its SD, kind of like the copper bullets today. Im sure Bell used fmj on elephants.

What’s changed is the impact speed that blows up softer bullets. A 170 grain round nose works great in a 30-30 but put the same bullet in a 300 Winchester at 3000fps and shoot something at 100 yards and you have a mess.

The challenge for bullets manufacturers and hunters today is choosing the right caliber with the right bullet considering the distance you anticipate shooting. The bullet needs to hold together so the bigger the animal you are hunting deeper penetration you need to cleanly kill the more SD you need to maintain. The faster you shooting the bullet the tougher bullet you need to maintain the SD of the bullet as it travels through flesh and bone. It’s a delicate balance and we have more choices today than hunters have ever had.