Does anybody know if the b.c. stated by Hornady for the 208 gr. A-Max is accurate? I know Bryan Litz lists real world b.c.s for several bullets in his book. (which I don't have yet)I was just wondering if it's listed, or if Hornady's number is close.
Range Report A-Max b.c.
- Thread starter trigger29
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Re: A-Max b.c.
I have found the published BC to be accurate.
I have found the published BC to be accurate.
Re: A-Max b.c.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bigwheels</div><div class="ubbcode-body">I have found the published BC to be accurate. </div></div>
JBM with Litz's numbers have worked very well for me out past 2000 yards.
John
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bigwheels</div><div class="ubbcode-body">I have found the published BC to be accurate. </div></div>
JBM with Litz's numbers have worked very well for me out past 2000 yards.
John
Re: A-Max b.c.
Is that with the G7 BC? My FFS program only does the G1, & I've found the .649 G1 to be accurate out to 2K yds. But I don't know what Litz's numbers are.
Is that with the G7 BC? My FFS program only does the G1, & I've found the .649 G1 to be accurate out to 2K yds. But I don't know what Litz's numbers are.
Re: A-Max b.c.
Pretty sure it's G1. I just scroll down the menu, pick 208 Amax (Litz), put in the rest of my parameters...
I DO know that it's a lot flatter if I just pick the stock 208 #'s.
The last time I went out it was within .2 mils t 1925 yds. at AO I've never shot at before.
John
Pretty sure it's G1. I just scroll down the menu, pick 208 Amax (Litz), put in the rest of my parameters...
I DO know that it's a lot flatter if I just pick the stock 208 #'s.
The last time I went out it was within .2 mils t 1925 yds. at AO I've never shot at before.
John
Re: A-Max b.c.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jrob300</div><div class="ubbcode-body">Pretty sure it's G1. I just scroll down the menu, pick 208 Amax (Litz), put in the rest of my parameters...
I DO know that it's a lot flatter if I just pick the stock 208 #'s.
The last time I went out it was within .2 mils t 1925 yds. at AO I've never shot at before.
John </div></div>
Anything with "(Litz)" in the description is a G7.
Thanks!
Brad
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jrob300</div><div class="ubbcode-body">Pretty sure it's G1. I just scroll down the menu, pick 208 Amax (Litz), put in the rest of my parameters...
I DO know that it's a lot flatter if I just pick the stock 208 #'s.
The last time I went out it was within .2 mils t 1925 yds. at AO I've never shot at before.
John </div></div>
Anything with "(Litz)" in the description is a G7.
Thanks!
Brad
Re: A-Max b.c.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JBM</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jrob300</div><div class="ubbcode-body">Pretty sure it's G1. I just scroll down the menu, pick 208 Amax (Litz), put in the rest of my parameters...
I DO know that it's a lot flatter if I just pick the stock 208 #'s.
The last time I went out it was within .2 mils t 1925 yds. at AO I've never shot at before.
John </div></div>
Anything with "(Litz)" in the description is a G7.
Thanks!
Brad </div></div>
Good to know...
thanks,
John
<span style="font-weight: bold">EDIT:</span> LOVE your ballistics program!
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JBM</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jrob300</div><div class="ubbcode-body">Pretty sure it's G1. I just scroll down the menu, pick 208 Amax (Litz), put in the rest of my parameters...
I DO know that it's a lot flatter if I just pick the stock 208 #'s.
The last time I went out it was within .2 mils t 1925 yds. at AO I've never shot at before.
John </div></div>
Anything with "(Litz)" in the description is a G7.
Thanks!
Brad </div></div>
Good to know...
thanks,
John
<span style="font-weight: bold">EDIT:</span> LOVE your ballistics program!
Re: A-Max b.c.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jrob300</div><div class="ubbcode-body"> LOVE your ballistics program!</div></div>
Big +1. Been using it for years and it has never let me down yet.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jrob300</div><div class="ubbcode-body"> LOVE your ballistics program!</div></div>
Big +1. Been using it for years and it has never let me down yet.
Re: A-Max b.c.
I use JBM to see differences that I can't account for with FFS, & it has been good for that. I just wish they had a mobile program when I purchased FFS years ago.
I use JBM to see differences that I can't account for with FFS, & it has been good for that. I just wish they had a mobile program when I purchased FFS years ago.
Re: A-Max b.c.
It figures, I post yesterday, and got a response from another source today from someone with Litz's book in hand.
"A-max BCs: G1 - .633, G7 - .324."
Thanks for all your responses guys. I think I can call it close enough for the shooting I do.......Which I'm pretty sure will be inside 2000 yards. That's impressive.
It figures, I post yesterday, and got a response from another source today from someone with Litz's book in hand.
"A-max BCs: G1 - .633, G7 - .324."
Thanks for all your responses guys. I think I can call it close enough for the shooting I do.......Which I'm pretty sure will be inside 2000 yards. That's impressive.
Re: A-Max b.c.
Ok guy don't bash me too hard now but I've always seen G1 BC numbers stated, whats thr G7 number used for and whats the difference between them? Also are their more like G2, G3, G4, etc?
Thanks guys
Ok guy don't bash me too hard now but I've always seen G1 BC numbers stated, whats thr G7 number used for and whats the difference between them? Also are their more like G2, G3, G4, etc?
Thanks guys
Re: A-Max b.c.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MrLebowski</div><div class="ubbcode-body">Ok guy don't bash me too hard now but I've always seen G1 BC numbers stated, whats thr G7 number used for and whats the difference between them? Also are their more like G2, G3, G4, etc?
Thanks guys </div></div>
They refer to the type standard that the ballistic coefficient is calculated against. The G1 is a standard for a flat based, spitzer type bullet that is calculated from a similarly shaped artillery shell.
There are numerous others, including a G2, G5, G7, G8, G10.
The G7 makes a good representation of the regular, swaged core, jacketed type bullets such as the boat tailed long range match projectiles.
For the extremely long, monolithic bullets in the 6-7 caliber length range (ie, a 7 caliber 30c bullet is 7*0.308 ~ 2.2" long)then different standards are needed because the G7 and G1 don't fit those curves particularly well.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MrLebowski</div><div class="ubbcode-body">Ok guy don't bash me too hard now but I've always seen G1 BC numbers stated, whats thr G7 number used for and whats the difference between them? Also are their more like G2, G3, G4, etc?
Thanks guys </div></div>
They refer to the type standard that the ballistic coefficient is calculated against. The G1 is a standard for a flat based, spitzer type bullet that is calculated from a similarly shaped artillery shell.
There are numerous others, including a G2, G5, G7, G8, G10.
The G7 makes a good representation of the regular, swaged core, jacketed type bullets such as the boat tailed long range match projectiles.
For the extremely long, monolithic bullets in the 6-7 caliber length range (ie, a 7 caliber 30c bullet is 7*0.308 ~ 2.2" long)then different standards are needed because the G7 and G1 don't fit those curves particularly well.
Re: A-Max b.c.
MrLebowski, most of the bullets you use will fit either the G1 or G7 drag model. As bohem stated, G7 fits most boat tails pretty well. The important thing is to have an accurate number, regardless of the model used. In fact, at ranges out to 500-600 yards, you'll almost see no difference in drops between the G1 BC and the G7 BC. Beyond that, you certainly will.
Yet another advantage of having Litz' Applied Ballistics book is that there are numbers published for a lot of bullets. If you look at the table for each bullet, you'll see both a G1 and a G7 BC published for each. There's also a valuable clue for which drag model is best suited for that bullet - the variation from the average. While most of the projectiles he tested are boat tails some, such as the 200-gr .308 Nosler Partition, have less variation (as measured across different speeds) from the G1 model.
MrLebowski, most of the bullets you use will fit either the G1 or G7 drag model. As bohem stated, G7 fits most boat tails pretty well. The important thing is to have an accurate number, regardless of the model used. In fact, at ranges out to 500-600 yards, you'll almost see no difference in drops between the G1 BC and the G7 BC. Beyond that, you certainly will.
Yet another advantage of having Litz' Applied Ballistics book is that there are numbers published for a lot of bullets. If you look at the table for each bullet, you'll see both a G1 and a G7 BC published for each. There's also a valuable clue for which drag model is best suited for that bullet - the variation from the average. While most of the projectiles he tested are boat tails some, such as the 200-gr .308 Nosler Partition, have less variation (as measured across different speeds) from the G1 model.
Re: A-Max b.c.
First, understand that BC is not some absolute property. It's not like mass or volume or hardness, it's a completely artificial, completely made-up number that's meant to aid in calculating a bullet's ability to penetrate the air. And regardless of which BC we're talking about (G1 or G7 or whatever), it isn't a constant, unchanging number. It changes as velocity changes.
According to Bryan Litz's <span style="font-style: italic">Applied Ballistics For Long Range Shooting</span> (ISBN 978-0-615-27661-8, $39.95 at finer reloading shops and bookstores everywhere), the 208-gr A-Max's G1 BC (averaged from 1500-3000 fps) is 0.633.
Yes, Bryan does publish his own G1 BCs, in part to demonstrate that the manufacturers are publishing data that is not derived from sound scientific testing, and in part to demonstrate the inadequacies of G1 when working with VLD bullets. In his book, he describes in great detail how he takes these measurements, and what methods he uses to guarantee his error rate is less than 1%.
BC is about the ability to penetrate air. If a bullet were fired in a vacuum, the arc of its path of flight would be predicted entirely by its acceleration earthward due to gravity. But because a bullet must also overcome wind resistance, it will tend to fall to earth more steeply than gravity alone could account for. The trick is in predicting how much more the trajectory will steepen because of drag.
Suppose you were to take a VW Microbus and a Corvette and weigh them. Then add a pile of bricks into whichever weighs less so that they both weigh the same. Run them both up to 60 mph. At that point, both vehicles possess an identical amount of kinetic energy. Then you push in the clutch and let them coast to a stop. Which one will roll further?
Obviously, the Vette will roll further because it is much more streamlined. Starting with exactly the same kinetic energy, the Vette will roll further because it penetrates the air more efficiently.
Based on how quickly they coast down, you can write a formula to predict how far either of them would roll if left to coast down from 45 mph ...or from 80. That's what a ballistic software does for you. You tell it how fast your bullet will be going at the muzzle, and it calculates your bullet's acceleration earthward due to gravity, adds in the slowing due to drag, and comes up with a calculated trajectory. But the formula for the Vette wouldn't work on the VW and the formula for the VW wouldn't work on the Vette.
Why? Because their drag is very different. In ballistic-speak, the two have a different "form factor." In a nutshell, that's what G1 and G7 represent, two bullets with drastically different form factors.
The G1, in fact, was based on a late-1800s artillery shell with a short ogive and a flat base. Bryan wrote G7 to describe the drag characteristics of low-drag, high-ogive, boattailed bullets such as those he's designed for Berger. So my VW-vs-Vette comparison isn't too far from the real differences.
If you buy Bryan's book (<span style="font-style: italic">Applied Ballistics For Long Range Shooting</span>, ISBN 978-0-615-27661-8, $39.95 at finer reloading shops and bookstores everywhere), there's a CD inside with a program written in Java on it called the Point Mass Ballistics Solver. As you might have guessed, it "understands" the G7 form factor. There's a note in Chapter 8: Using Ballistics Programs that says the application is available free on the internet. I've got the CD so I haven't looked for it but I take him at his word. But the app is only 64 kb (yes, I meant kilobytes!) so if you can find it, it won't be too demanding to download.
It only accepts a single, averaged (G7) BC, not multiple "banded" BCs, but it also has built-in spin-drift and stability calculators. Definitely worth tracking down.
First, understand that BC is not some absolute property. It's not like mass or volume or hardness, it's a completely artificial, completely made-up number that's meant to aid in calculating a bullet's ability to penetrate the air. And regardless of which BC we're talking about (G1 or G7 or whatever), it isn't a constant, unchanging number. It changes as velocity changes.
According to Bryan Litz's <span style="font-style: italic">Applied Ballistics For Long Range Shooting</span> (ISBN 978-0-615-27661-8, $39.95 at finer reloading shops and bookstores everywhere), the 208-gr A-Max's G1 BC (averaged from 1500-3000 fps) is 0.633.
Yes, Bryan does publish his own G1 BCs, in part to demonstrate that the manufacturers are publishing data that is not derived from sound scientific testing, and in part to demonstrate the inadequacies of G1 when working with VLD bullets. In his book, he describes in great detail how he takes these measurements, and what methods he uses to guarantee his error rate is less than 1%.
BC is about the ability to penetrate air. If a bullet were fired in a vacuum, the arc of its path of flight would be predicted entirely by its acceleration earthward due to gravity. But because a bullet must also overcome wind resistance, it will tend to fall to earth more steeply than gravity alone could account for. The trick is in predicting how much more the trajectory will steepen because of drag.
Suppose you were to take a VW Microbus and a Corvette and weigh them. Then add a pile of bricks into whichever weighs less so that they both weigh the same. Run them both up to 60 mph. At that point, both vehicles possess an identical amount of kinetic energy. Then you push in the clutch and let them coast to a stop. Which one will roll further?
Obviously, the Vette will roll further because it is much more streamlined. Starting with exactly the same kinetic energy, the Vette will roll further because it penetrates the air more efficiently.
Based on how quickly they coast down, you can write a formula to predict how far either of them would roll if left to coast down from 45 mph ...or from 80. That's what a ballistic software does for you. You tell it how fast your bullet will be going at the muzzle, and it calculates your bullet's acceleration earthward due to gravity, adds in the slowing due to drag, and comes up with a calculated trajectory. But the formula for the Vette wouldn't work on the VW and the formula for the VW wouldn't work on the Vette.
Why? Because their drag is very different. In ballistic-speak, the two have a different "form factor." In a nutshell, that's what G1 and G7 represent, two bullets with drastically different form factors.
The G1, in fact, was based on a late-1800s artillery shell with a short ogive and a flat base. Bryan wrote G7 to describe the drag characteristics of low-drag, high-ogive, boattailed bullets such as those he's designed for Berger. So my VW-vs-Vette comparison isn't too far from the real differences.
If you buy Bryan's book (<span style="font-style: italic">Applied Ballistics For Long Range Shooting</span>, ISBN 978-0-615-27661-8, $39.95 at finer reloading shops and bookstores everywhere), there's a CD inside with a program written in Java on it called the Point Mass Ballistics Solver. As you might have guessed, it "understands" the G7 form factor. There's a note in Chapter 8: Using Ballistics Programs that says the application is available free on the internet. I've got the CD so I haven't looked for it but I take him at his word. But the app is only 64 kb (yes, I meant kilobytes!) so if you can find it, it won't be too demanding to download.
It only accepts a single, averaged (G7) BC, not multiple "banded" BCs, but it also has built-in spin-drift and stability calculators. Definitely worth tracking down.
Re: A-Max b.c.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fred_C_Dobbs</div><div class="ubbcode-body">The G1, in fact, was based on a late-1800s artillery shell with a short ogive and a flat base. Bryan wrote G7 to describe the drag characteristics of low-drag, high-ogive, boattailed bullets such as those he's designed for Berger. So my VW-vs-Vette comparison isn't too far from the real differences.</div></div>
You made an excellent comparison and a number of very salient points, however, I have a slight correction. Mr. Litz does indeed advocate the use of the G7 however he did not develop the standard. My understanding from various literature that has been published approximately the time that both Mr. Litz and myself were in grammar school is that the G7 was first published around WWI. It happens to lend itself nicely to the bullets that we commonly shoot and his contribution (among other things) is to push manufacturers to using and publishing G7 data for their more demanding clients.
My comments in the first post reflect some research that I've been involved with on the topic and found that if a G standard is needed to work from on something like an ultra agressive turned solid such as what Gerard Schultz and Lutz Moller are currently selling to clients, a different BC standard happens to make a better curve fit than a G1 or G7 standard (single value) result.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fred_C_Dobbs</div><div class="ubbcode-body">The G1, in fact, was based on a late-1800s artillery shell with a short ogive and a flat base. Bryan wrote G7 to describe the drag characteristics of low-drag, high-ogive, boattailed bullets such as those he's designed for Berger. So my VW-vs-Vette comparison isn't too far from the real differences.</div></div>
You made an excellent comparison and a number of very salient points, however, I have a slight correction. Mr. Litz does indeed advocate the use of the G7 however he did not develop the standard. My understanding from various literature that has been published approximately the time that both Mr. Litz and myself were in grammar school is that the G7 was first published around WWI. It happens to lend itself nicely to the bullets that we commonly shoot and his contribution (among other things) is to push manufacturers to using and publishing G7 data for their more demanding clients.
My comments in the first post reflect some research that I've been involved with on the topic and found that if a G standard is needed to work from on something like an ultra agressive turned solid such as what Gerard Schultz and Lutz Moller are currently selling to clients, a different BC standard happens to make a better curve fit than a G1 or G7 standard (single value) result.
Re: A-Max b.c.
Next you'll be telling me he didn't invent the Internet.
Seriously, bohem, thanks for straightening me out.
Next you'll be telling me he didn't invent the Internet.
Seriously, bohem, thanks for straightening me out.
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