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

[gregsjt]

If more people actually ran the numbers, they would be astounded at just how little difference there is in exterior ballistics out to 500 or 600 yards between the famously effective hunting bullets, like an A-Frame for example, and the super duper Bergers of the same weight. Out to just past 500 yards, muzzle velocity is the main component of trajectory. Only past this, does a superior BC start to really widen the gap in trajectory.

At 2,000 ft elevation:
A .696 BC 215 Berger at 2900 fps = 8.1 MOA, 2297 fps, 2342 ft.lbs at 500 yards.
A .444 BC 200 Swfit at 2900 fps = 9.3 MOA, 1989 fps, 1757 ft.lbs at 500 yards.

So, even with 250 BC points difference there is only 1.2 MOA difference in trajectory. The energies and impact velocities don't have to be the same, they just need to be adequate for penetration and expansion. If given the choice of making this shot with either one of these bullets at an elk, I'm choosing the A-Frame.

Sorry, one more point: What happens if you extend the range far enough that the velocity of the A-Frame drops below 1800 fps, yet the the Berger is going 2000 fps or faster? Do you still want to use that bullet?

All other factors being equal (terminal ballistics) why wouldn't you take the advantage that a high BC bullet gives you?

 

[User4302021]

Run your numbers for wind drift, no one really worries about elevation till your out to the end of your optic. We care about BC for wind drift and impact velocity of until I'm hitting 100+ moa and need more range but that not a hunting range.

You are of course correct about the wind drift being more (although not that much more, 10 mph = 1.8 moa for .696 BC and 3.0 moa for the .444 BC).

I chose 2 extremes simply to illustrate the point. Even the 200 grain Partition has .481 BC . There are good hunting bullets that are a much closer match, yet still proven performers on tough game.

But at it's root, the issue of wind is a training issue, people are always trying to solve training issues with equipment fixes. That is nothing new.

 

[FURMAN]

You are of course correct about the wind drift being more (although not that much more, 10 mph = 1.8 moa for .696 BC and 3.0 moa for the .444 BC).

I chose 2 extremes simply to illustrate the point. Even the 200 grain Partition has .481 BC . There are good hunting bullets that are a much closer match, yet still proven performers on tough game.

But at it's root, the issue of wind is a training issue, people are always trying to solve training issues with equipment fixes. That is nothing new.

That is an absolutely ridiculous statement. There are people who make spent brass for a living that still miss the x ring on long range targets with the best equipment and ballistics money can buy. All the training in the world will not fix the fact that wind is impossible to read 100% all of the time and I would say that it would be difficult to nail the wind even 50% of the time in field conditions, over terrain, up hillsides, down hillsides, etc... When you have rifles and loads that hold a solid water line it will be very easy to see how much bc matters. The bullet reaching the vitals of an animal does not know what MOA is it only knows inches and one inch could be the difference between a clean kill and a 2 mile track job through some of the nastiest terrains. I will take the bc and stack the odds in my favor as much as possible.

 

[bigngreen]

You are of course correct about the wind drift being more (although not that much more, 10 mph = 1.8 moa for .696 BC and 3.0 moa for the .444 BC).

I chose 2 extremes simply to illustrate the point. Even the 200 grain Partition has .481 BC . There are good hunting bullets that are a much closer match, yet still proven performers on tough game.

But at it's root, the issue of wind is a training issue, people are always trying to solve training issues with equipment fixes. That is nothing new.

I don't even know how to explain how wrong that is! That's more than an MOA of advantage at that close of a distance no less, I'll take that every day of the week and twice on Sunday!
Not taking advantage of the best BC you can in the bullet design your looking for is like saying using a range finder is a training issue or a wind meter is an equipment fix, I really can't even understand that mind set to be honest.

 

[FURMAN]

This video was a big bull tahr at 600 yards. This is typical Berger 215 performance. Please enlighten me on how it gets better?

https://i.imgur.com/y6jFypQl.mp4

Here is one a 250.

https://i.imgur.com/tGgvEBhl.mp4

 

[User4302021]

That is an absolutely ridiculous statement. There are people who make spent brass for a living that still miss the x ring on long range targets with the best equipment and ballistics money can buy.

So the vitals on an elk are the same size as the X-ring on a NRA target?

All the training in the world will not fix the fact that wind is impossible to read 100% all of the time and I would say that it would be difficult to nail the wind even 50% of the time in field conditions, over terrain, up hillsides, down hillsides, etc...

If if it is indeed THAT difficult, then why are we discussing the attempt?

 

[User4302021]

I don't even know how to explain how wrong that is! That's more than an MOA of advantage at that close of a distance no less, I'll take that every day of the week and twice on Sunday!
Not taking advantage of the best BC you can in the bullet design your looking for is like saying using a range finder is a training issue or a wind meter is an equipment fix, I really can't even understand that mind set to be honest.

I would assume that you would have a proper wind chart made up for your hunting round, regardless of the BC.

If you can't be sufficiently confident in your wind reading ability to make the hit a the distance you are shooting...then why are you taking the shot?

For the type of hunting we are talking about, a rangefinder is unfortunately a necessity. Gravity affects a bullet much more than wind, therefore range is the more critical of the two.

The wind meter is a crutch and a liar. It will only give wind speed at the firing position. So that IS a training issue.

 

[bigngreen]

I would assume that you would have a proper wind chart made up for your hunting round, regardless of the BC.

If you can't be sufficiently confident in your wind reading ability to make the hit a the distance you are shooting...then why are you taking the shot?

For the type of hunting we are talking about, a rangefinder is unfortunately a necessity. Gravity affects a bullet much more than wind, therefore range is the more critical of the two.

The wind meter is a crutch and a liar. It will only give wind speed at the firing position. So that IS a training issue.

I use wind maps I've created from shooting the areas through the year and real time solutions.

I have confidence because I know I'm minimizing error at every place possible then giving myself more room for small error.

A wind meter when combined with wind reading knowledge is one of the most valuable tools but you have to TRAIN with it and know how to use it in conjunction with other cues, if you screw up the wind nearest to you which counts the most all of your other calls won't matter, a wind meter certainly gives me a base line to go to work with.
The largest wind error I've missed on game beyond 1000 yards is right at 6 inches, I always miss my read down wind so I always shoot my game so any error puts it through the shoulder instead of liver.

 

[turkn8r1]

OK let's take this in another direction. I think this all started with a thread about sectional density. I'm so confused right now I actually believe what my wife is saying. OK let's take 2 projectiles. Same shape same BC same SD same speed but 2 different typed of material and construction. Like let's say a VLD Target and a long range accubond. Theoretically they both fly the same. They both drift the same (spin which no one has mentioned and wind). They should have the same speed energy and velocity at impact, Now what happens and which factor is most important. This is not to incite a riot but so far there have been some interesting thought provoking and informative information come from this. So let's hear some thoughts and theories. I am not saying any one factor is more important. I do think that how we individually look at it will dictate how this goes. And most importantly we can definitely learn from each other and our varied experiences. We are all adults (except when no one's watching) so let's stay civil and learn something.

 

[Alibiiv]

OK let's take this in another direction. I think this all started with a thread about sectional density. I'm so confused right now I actually believe what my wife is saying. OK let's take 2 projectiles. Same shape same BC same SD same speed but 2 different typed of material and construction. Like let's say a VLD Target and a long range accubond. Theoretically they both fly the same. They both drift the same (spin which no one has mentioned and wind). They should have the same speed energy and velocity at impact, Now what happens and which factor is most important. This is not to incite a riot but so far there have been some interesting thought provoking and informative information come from this. So let's hear some thoughts and theories. I am not saying any one factor is more important. I do think that how we individually look at it will dictate how this goes. And most importantly we can definitely learn from each other and our varied experiences. We are all adults (except when no one's watching) so let's stay civil and learn something.

Yes "sectional density"!​

 

[Mikecr]

I'm so confused right now I actually believe what my wife is saying.

Round here we refer to that as 'lost as a nine-eyed dog'

 

[gregsjt]

I think the bottom line is that sectional density is irrelevant if you're already using BC to compare bullets. The formula for BC is Mass/(Cross Sectional Diameter * Coefficient of Form). The formula for sectional density is mass/cross sectional area. So you already have a close component of sectional density built into the formula for BC.

Let's look at two bullets from Hornady as an example: https://www.hornady.com/bullets/rifle/#!/

Both are 220 grain, both have the exact same sectional density, .331. Both have proven to be effective on game, yet one has a BC of .65 and the .3. Unless you are using a lever action or need a round nose for some other non-ballistic related reason, why would you ever choose the round nose? @Dog Rocket already showed us the difference in exterior ballistics at 500 yards and @rfurman24 pointed out the difference in wind drift. I do not understand why you would purposely handicap yourself when shooting at a living animal, makes no sense.

 

[bigngreen]

OK let's take this in another direction. I think this all started with a thread about sectional density. I'm so confused right now I actually believe what my wife is saying. OK let's take 2 projectiles. Same shape same BC same SD same speed but 2 different typed of material and construction. Like let's say a VLD Target and a long range accubond. Theoretically they both fly the same. They both drift the same (spin which no one has mentioned and wind). They should have the same speed energy and velocity at impact, Now what happens and which factor is most important. This is not to incite a riot but so far there have been some interesting thought provoking and informative information come from this. So let's hear some thoughts and theories. I am not saying any one factor is more important. I do think that how we individually look at it will dictate how this goes. And most importantly we can definitely learn from each other and our varied experiences. We are all adults (except when no one's watching) so let's stay civil and learn something.

This is a good comparison to see they whys somethings happen that seem not logical, the VLD opens based on hydraulic pressure in the tip forcing open the tip sometimes blowing it of exposing the lead and jacket to start mushrooming. The ABLR opens to to mechanical force pushing the tip back and starting opening then it moves to the side exposing a larger cavity. When cutting large volumes of game you'll find plastic tips in the entry wound all the time, never inside the animal or of side.
The VLD being not bonded and the ABLR being bonded but softer lead, in close hits I've seen the VLD delayed opening make it into the animal before you start seeing signs of expansion, then the tip blows and a portion goes into a cloud of frag right in the core, but it's does not create a lot of frontal area so if less SD remains it's enough to continue pushing the bullet through if it's in a speed range that the jacket does not separate and the lead breaks in which case you'll see cut marks and frag in the inside of the ribs. The farther you get the less the jacket is stressed and it will stop ripping and you'll see consistent exits.
The ABLR you'll see immediate surface wounding all the way into the ribs because expansion is initiated on the hide, the tips seem to blow of and creates a mushroom due to bonding but smaller than a regular AB, I've seen these bullets damage the onside lungs impressively but the rest of the way through it's a 3/4-1 inch bruised hole where the expansion has stopped. At close range you'll find a waded up ball of lead under the hide at longer range the shank exits. The bonded bullets have issues in the velocity range where they open big and expand but it's to the point they loose to much SD to over come the frontal area that won't shear of or fold back against the shank. This is what I've seen in elk.
For me SD and frontal diameter is some key factors when I look at a bullet, I want them balanced so the bullets will penetrate through the on side but still do a lot of mechanical damage once in the core. Get one of and you'll see bullets penciling or bullets stopping on an elk shoulder like a Barnes or AB because their SD is to low for the frontal area, where a VLD will get small and retain enough SD to get into the core.

 

[User4302021]

OK let's take this in another direction. I think this all started with a thread about sectional density. I'm so confused right now I actually believe what my wife is saying. OK let's take 2 projectiles. Same shape same BC same SD same speed but 2 different typed of material and construction. Like let's say a VLD Target and a long range accubond. Theoretically they both fly the same. They both drift the same (spin which no one has mentioned and wind). They should have the same speed energy and velocity at impact, Now what happens and which factor is most important. This is not to incite a riot but so far there have been some interesting thought provoking and informative information come from this. So let's hear some thoughts and theories. I am not saying any one factor is more important. I do think that how we individually look at it will dictate how this goes. And most importantly we can definitely learn from each other and our varied experiences. We are all adults (except when no one's watching) so let's stay civil and learn something.

Well, the confusing part is that Sectional Density is involved in BOTH external ballistics (it is inextricable from BC) and terminal ballistics (the higher the SD the more tendency for a bullet to track straight through a highly resistant medium.)

What we are really hashing out is the balance between the shape of the bullet (Drag Coefficient) vs. the compromises that have to be made to bullet construction to achieve that slippery shape. At least that is the way I'm looking at this.