Sectional Density - Desert Dog

[dchum]

Tissue damage is a result of expansion and penetration.

Obviously solids penetrate the deepest, but at the expense of no expansion. Unbonded softs expand the most, but at the expense of penetration.

SD only informs on the potential for penetration. Higher SD speaks to a greater potential for penetration than lower.

I'm pretty sure you could get this fellow up to 2700 or 2800 out of a 458 Lott
View attachment 747738

But I'm also pretty sure nobody's hunting cape buffalo with it, either.

Yes but that little cutting edge bullet would out penetrate a 500 gr Northfork on a buffalo 100%

Thats where SD looses me.

So what are we measuring? I feel like with both have our sides so not looking to argue.

 

[DaddyFlip]

Sectional density is a ballistic buzzword that is oversold by the bullet industry and overvalued by the hunting community. As mass increases within a diameter, SD will naturally increase - it's just a mathematical formula. A 7mm 168gr bullet will have a higher SD than a .308 168 gr bullet; so what? Two bullets of equal mass but of UNequal diameter will have different SD; the smaller diameter will have a higher SD and will be longer. This is the selling point of SD- that the longer but lesser diameter bullet has more mass behind the tip or meplat and will penetrate deeper due to lower frontal area. OTOH, there are proponents of frontal area and bullet diameter over everything else.

In the never ending pursuit of better marketing and greater sales, a new metric comes to the fore. I can remember when SD didn't exist and BC was at the fore. Before that, your forefathers cared for neither. Before that, their forefathers hunted with gunpowder and lead balls. Before that, their forefathers hunted with spears. Don't get hung up on SD; it's irrelevant. It's mass times veliocity squared that kills... and good shot placement.

 

[Red Leg]

I am older than many here, and until the wealth of field data is available actually proving that SD is "oversold," I think I will stick with what actually has been proven for a bit over a hundred years - greater SD equals greater penetration. Were I hunting a buff tomorrow with one of my .375's it would be with a 300 gr bullet or heavier. Were the bullet a TSX, it would still be at least 300 grs. Theoretically, a 270 gr TSX might be just as effective and over longer ranges - but who is shooting a buffalo at longer range? SD isn't the end all, but it is the best measure I have found for penetration without relying on the manufacturers bullet design to make up for it.

 

[375Fox]

Yes but that little cutting edge bullet would out penetrate a 500 gr Northfork on a buffalo 100%

Thats where SD looses me.

So what are we measuring? I feel like with both have our sides so not looking to argue.

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.

 

[DaddyFlip]

I am older than many here, and until the wealth of field data is available actually proving that SD is "oversold," I think I will stick with what actually has been proven for a bit over a hundred years - greater SD equals greater penetration. Were I hunting a buff tomorrow with one of my .375's it would be with a 300 gr bullet or heavier. Were the bullet a TSX, it would still be at least 300 grs. Theoretically, a 270 gr TSX might be just as effective and over longer ranges - but who is shooting a buffalo at longer range? SD isn't the end all, but it is the best measure I have found for penetration without relying on the manufacturers bullet design to make up for it.

I would never challenge anyone's personal experience and you are almost making my mathematical point. You are speaking of increasing mass within the same diameter, and there is no argument against that. The 'modern' proponents of SD suggest that a smaller diameter of equal mass is better. Here are a handful of potential/traditional 300gr African calibers in descending order of SD; what is your choice for buffalo if bullet construction is identical? The highest SD is 338 Win Mag; the lowest is 458 Win Mag.

338 Win Mag
9.3 x 62
375 H&H
405 Winchester
416 Rigby
458 Win Mag

 

[Killingtime]

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.

 

[CoElkHunter]

Sectional density is a ballistic buzzword that is oversold by the bullet industry and overvalued by the hunting community. As mass increases within a diameter, SD will naturally increase - it's just a mathematical formula. A 7mm 168gr bullet will have a higher SD than a .308 168 gr bullet; so what? Two bullets of equal mass but of UNequal diameter will have different SD; the smaller diameter will have a higher SD and will be longer. This is the selling point of SD- that the longer but lesser diameter bullet has more mass behind the tip or meplat and will penetrate deeper due to lower frontal area. OTOH, there are proponents of frontal area and bullet diameter over everything else.

In the never ending pursuit of better marketing and greater sales, a new metric comes to the fore. I can remember when SD didn't exist and BC was at the fore. Before that, your forefathers cared for neither. Before that, their forefathers hunted with gunpowder and lead balls. Before that, their forefathers hunted with spears. Don't get hung up on SD; it's irrelevant. It's mass times veliocity squared that kills... and good shot placement.

Whatever happened to BC? I too remember that was a big selling point for bullets back in the day. But you’re right about our forefathers didn’t think or care about either SD or BC. Most bought what was available and inexpensive. I would venture to say that the vast majority of hunters worldwide today buy their hunting ammo within those same parameters: availability and cost.

 

[DaddyFlip]

Whatever happened to BC? I too remember that was a big selling point for bullets back in the day. But you’re right about our forefathers didn’t think or care about either SD or BC. Most bought what was available and inexpensive. I would venture to say that the vast majority of hunters worldwide today buy their hunting ammo within those same parameters: availability and cost.

I'm not sure, but I think that BC may have peaked in the Weatherby heyday then died out after the 'beanfield rifle' craze vanished. It's still an important aspect of bullet design, but it's not that important to modern hunters. It's been shown that FB bullets may have better accuracy and terminal performance than BT bullets of equal weight, even though their BC is higher. So what if a well-designed BT bullet drops an inch or two less at 400 yards? It could be that the combination of FB and 100% copper construction is winning the day over more traditional designs (i.e. someone with a better mousetrap, even if it's marketing, is driving the market in a different direction). Look, SD was always there, it just wasn't a selling point. What sells today is smaller diameters and faster velocities. If you can find a way to sell more smaller diameter calibers, you can win in the modern age. SD helps you do that if you can 'fast twist' a rifle to sling a longer, heavier bullet.

 

[CoElkHunter]

I would never challenge anyone's personal experience and you are almost making my mathematical point. You are speaking of increasing mass within the same diameter, and there is no argument against that. The 'modern' proponents of SD suggest that a smaller diameter of equal mass is better. Here are a handful of potential/traditional 300gr African calibers in descending order of SD; what is your choice for buffalo if bullet construction is identical? The highest SD is 338 Win Mag; the lowest is 458 Win Mag.

338 Win Mag
9.3 x 62
375 H&H
405 Winchester
416 Rigby
458 Win Mag

Very interesting. Now add the BC for different bullets for each cartridge just to increase the confusion. LOL

 

[DaddyFlip]

Very interesting. Now add the BC for different bullets for each cartridge just to increase the confusion. LOL

As is my custom, I was about to take up that challenge, but I'll rest my case that SD 100 years ago didn't mean the same thing to the hunter as is marketed today. John Taylor would have said that bullet diameter was the most important thing (given adequate and equal velocity; hence, his Taylor KO value). If we polled a dozen experienced AH hunters, would they rather hunt buffalo with a 300gr 375 @ 2600FPS or a 300gr 416 at 2800FPS, just as an example? Maybe these two are equivalent? What if they were loaded at equal velocity?

 

[Killingtime]

High Ballistic coefficient has no real importance on a 5ft to 200 yard shot on any dangerous game. I like the tko factor I know many people who disagree with it but I’ve seen so many animals get flatline by big wide bullets from slower moving rounds to not believe that bullet diameter matters.

 

[375Fox]

Whatever happened to BC? I too remember that was a big selling point for bullets back in the day. But you’re right about our forefathers didn’t think or care about either SD or BC. Most bought what was available and inexpensive. I would venture to say that the vast majority of hunters worldwide today buy their hunting ammo within those same parameters: availability and cost.

What do you mean back in the day? I think BC is a problem now. They are marketing long range bullets with high BC over proper hunting bullets for standard ranges. All the long sleek bullets out now Hornady ELDX, Norma bondstrike, Federal terminal ascent, all Berger bullets. More traditional hunting bullets are losing market share.

 

[CoElkHunter]

As is my custom, I was about to take up that challenge, but I'll rest my case that SD 100 years ago didn't mean the same thing to the hunter as is marketed today. John Taylor would have said that bullet diameter was the most important thing (given adequate and equal velocity; hence, his Taylor KO value). If we polled a dozen experienced AH hunters, would they rather hunt buffalo with a 300gr 375 @ 2600FPS or a 300gr 416 at 2800FPS, just as an example? Maybe these two are equivalent? What if they were loaded at equal velocity?

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.

 

[Tradmark]

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

 

[CoElkHunter]

What do you mean back in the day? I think BC is a problem now. They are marketing long range bullets with high BC over proper hunting bullets for standard ranges. All the long sleek bullets out now Hornady ELDX, Norma bondstrike, Federal terminal ascent, all Berger bullets. More traditional hunting bullets are losing market share.

Good point.

 

[375Fox]

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

I agree. It’s a redesigned trophy bonded bear claw. I just don’t like the direction things are going. I wonder how long before the more traditional trophy bonded tip is phased out?

 

[DaddyFlip]

What do you mean back in the day? I think BC is a problem now. They are marketing long range bullets with high BC over proper hunting bullets for standard ranges. All the long sleek bullets out now Hornady ELDX, Norma bondstrike, Federal terminal ascent, all Berger bullets. More traditional hunting bullets are losing market share.

Good observation. Like SD, BC today doesn't carry the same message as 'back in the day'. I'll keep this part short. The big sale today is smaller diameters and faster velocities in lighter rifles firing at game at longer distances. Why? Maybe because it makes for good social media content? We're beyond the beanfield era of terminal ballistics. So what if you wound a feral hog at 600 yards? As long as it eventually dies, right?

Back to the SD topic, I just watched the beginning of the OP video. I like Desert Dog and have watched several of his videos. I agree with his SD assessment that it's not important as relates to modern bullet design. If we're talking about solids of equal construction, then it matters. Even then, I think (but I don't know) that experienced hunters would say that larger caliber is more important at equal weight and even better at heavier weight.

 

[Killingtime]

What do you mean back in the day? I think BC is a problem now. They are marketing long range bullets with high BC over proper hunting bullets for standard ranges. All the long sleek bullets out now Hornady ELDX, Norma bondstrike, Federal terminal ascent, all Berger bullets. More traditional hunting bullets are losing market share.

hammer bullets are cool for a high bc monolithic hunting option though like you said most of the options you mentioned are long range hunting fade bullets that do nothing over a old nosler partition in practice hunting distances.

 

[Tradmark]

Too many variables to say sectional density is a thing to worry to much about unless all else (variable) are accounted for. In the pistol world there are too many examples where copper solids basically always out penetrate other solid, non monolithic solids despite a significant deficit in sectional density. Michael from ceb bullets did some of the most detailed and in depth testing on penetration ever done. Sectional density wasnt in the podium position for most important factors in penetration

 

[CoElkHunter]

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

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