BC Article- Link

[RockZ]

The report I was quoting in my previous" BC/Drop" thread is from the November 2009 issue of GUNS magazine from an article named
"Ballistic Coefficient"
Here's a link -go to page 16
http://www.gunsmagazine.com/digital/GN1109.htm?page=16

 

[Chas1]

Good read, thanks for posting.

 

[Jon A]

This is a good example why I don't read many gun magazines anymore. Most gunwriters, especially those in hunting magazines, are very non-technical people who simply don't have much understanding of ballistics and other technical subjects. JB has vast experience and knowledge on general hunting subjects, but ballistics, LR shooting and hunting, etc...sometimes I wish people would stick to writing about what they know.

 

[Chas1]

Jon A, sounds like you may be upset with JB's article. Just curious if you are, what was it in the article that he said about ballistics, LR shooting and hunting, that makes you wish he'd write about what he knows?

 

[Jon A]

I'm not upset in the slightest. Just pointing out the obvious. If you'd like specifics from that article:

1) He gives the impression BC's are only valid under standard sea level conditions. Of course every ballistics program in existence will compensate for your actual environmental conditions so a sea level corrected BC is what you want. Using that method you can get accurate results anywhere you may happen to be on the planet. His mention of it gave the opposite impression.

2) The idea his crude drop measurements at 400 yds would be accurate enough to make comments on how long the bullet is yawing after the shot...quite laughable. The last time I saw him making ballistics comments based upon drops at 400 yds it turned out his group sizes were 9". Yes, 9". Hopefully this rifle shoots a bit better than that, but you get the point.

3) The overall impression the reader is left with is that BC's are not all that accurate and that they, along with ballistics software cannot be relied upon to accurately predict trajectory even out to only 400 yds. This is simply false. If he said 2000 yds, he could make a better case as that can get pretty darn difficult. But at only 400 yds if his results don't match predictions given accurate inputs it's due to flaws in his testing methods. But the article implies we should throw out all known exterior ballistic science because he got some phunky results once. I think this does a disservice to the readers.

And to give you another idea of where he's coming from, he has said elsewhere no scope used to hunt big game should have any sort of exposed turrets or parallax adjustment. If he doesn't need or want them for the type of hunting he does, that's fine. But it illustrates he isn't exactly a long range shooting/hunting enthusiast, much less authority.

Anyway, you asked so there you go. On subjects such as African hunting, tracking, other close range techniques, bullet terminal performance, etc, he is a wealth of information.

 

[Chas1]

I'm not upset in the slightest. Just pointing out the obvious. If you'd like specifics from that article:

1) He gives the impression BC's are only valid under standard sea level conditions. Of course every ballistics program in existence will compensate for your actual environmental conditions so a sea level corrected BC is what you want. Using that method you can get accurate results anywhere you may happen to be on the planet. His mention of it gave the opposite impression.

Jon A, thanks for responding. I got a different impression cause actually, he wrote "vary any of those conditions and BC varies as well. Elevation has the biggest effect.

2) The idea his crude drop measurements at 400 yds would be accurate enough to make comments on how long the bullet is yawing after the shot...quite laughable. The last time I saw him making ballistics comments based upon drops at 400 yds it turned out his group sizes were 9". Yes, 9". Hopefully this rifle shoots a bit better than that, but you get the point.

I don't see where he said how long the bullet was yawing. He wrote "Barrel/bullet/crown combination results in a much shorter period of yaw something apparently impossible to predict. When it does happen however the bullet will shoot alot flatter than in any computer model

3) The overall impression the reader is left with is that BC's are not all that accurate and that they, along with ballistics software cannot be relied upon to accurately predict trajectory even out to only 400 yds. This is simply false. If he said 2000 yds, he could make a better case as that can get pretty darn difficult. But at only 400 yds if his results don't match predictions given accurate inputs it's due to flaws in his testing methods. But the article implies we should throw out all known exterior ballistic science because he got some phunky results once. I think this does a disservice to the readers.

I respect your impression and what you thought was implied. I got a different impression as I didn't read that BC's are not all that accurate and that they, along with ballistics software cannot be relied upon to accurately predict trajectory or we should throw out all known exterior ballistic science.

And to give you another idea of where he's coming from, he has said elsewhere no scope used to hunt big game should have any sort of exposed turrets or parallax adjustment. If he doesn't need or want them for the type of hunting he does, that's fine. But it illustrates he isn't exactly a long range shooting/hunting enthusiast, much less authority.

Can you provide the article/writeup on no scope used to hunt big game should have any sort of exposed turrets or parallax adjustment. Let me know.

Anyway, you asked so there you go. On subjects such as African hunting, tracking, other close range techniques, bullet terminal performance, etc, he is a wealth of information.

Again, thanks for resonding. It's good to get others opinions.

 

[eddybo]

I like the article, thought it was a good non-technical read. But 400 yards is not gonna tell you shinola about the BC of a bullet. Exbal does not like his numbers for his junk science.

I do like the fact that the writer recognizes that BC is not a number you just plug into your ballistics program and go hunting. You have to shoot the **** things. Pus you have to shoot them at ranges further than you would shoot an animal. I have seen all kinds of strange stuff happening to BCs at longer ranges 1400+. Most of it can be compensated for by using multiple BCs or different form factors, but very rarely do the numbers give you your drops perfectly.

One way I have learned to mitigate slight errors in BC is to sight my rifles in at longer ranges. For instance, I usually sight my rifles in at 787 yards. If exbal proclaims that I need 12MOA for 787 yards I loosen the screws turn my dial to 12 and tighten them down. I then dial back to zero and should be zeroed in at 100 yards. Sometimes I end up 1/4 MOA +or- at 100 but find that it sort of slits the difference in any errors so that errors are masked at ranges past my 787 sight in distance.

 

[Jon A]

I got a different impression cause actually, he wrote "vary any of those conditions and BC varies as well. Elevation has the biggest effect.

Yes, that's what he wrote. And it's wrong. The standard conditions corrected BC (which is what you need to enter into ballistics programs) does not change as those conditions vary. Because it's corrected. That's the point.

People reading that will believe that advertised BC's, even if accurate, won't do them any good if they don't live at sea level. That's simply not correct. He did more harm than good.

I don't see where he said how long the bullet was yawing. He wrote "Barrel/bullet/crown combination results in a much shorter period of yaw something apparently impossible to predict. When it does happen however the bullet will shoot alot flatter than in any computer model

I don't see much distinction. Anyway, if he has identified a barrel/bullet/crown combination that really flies so much flatter than computer models predict, he could bottle it, sell it and be an instant millionaire.

Regardless, the point is that believing such crude and inaccurate measurement methods are sufficient to prove some radical theory that his particular rifle defies the laws of exterior ballistics is just silly, and it makes me sad so many readers will eat it up.

I didn't read that BC's are not all that accurate and that they, along with ballistics software cannot be relied upon to accurately predict trajectory or we should throw out all known exterior ballistic science.

May I respectfully suggest you read the article again. Because that's exactly what he said. BC's just can't be trusted. If you live the Rockies, your bullet may have a BC 20% higher than advertised (like the example he gives). If computer models can't predict trajectory well enough for you to hit the target at 400 yds, they aren't going to be within 10 feet at 1000 yds! Luckily, that's just not true.

Can you provide the article/writeup on no scope used to hunt big game should have any sort of exposed turrets or parallax adjustment. Let me know.

That was posted on another competing board so I probably shouldn't link. He has actually said much worse than that about long range hunters but wanted to stay out of that.

The point was when somebody not only doesn't practice your hobby but holds disdain for it, he might not be the best source of technical information and advice on the subject.

 

[Chas1]

Yes, that's what he wrote. And it's wrong. The standard conditions corrected BC (which is what you need to enter into ballistics programs) does not change as those conditions vary. Because it's corrected. That's the point.

He siad Standard Conditions only and referenced the Army's SMEC...vary any of those and BC changes...that's a fact

People reading that will believe that advertised BC's, even if accurate, won't do them any good if they don't live at sea level. That's simply not correct. He did more harm than good.

If that's what you take away from the article then I respect that. Thank goodness that's not what he said.

I don't see much distinction. Anyway, if he has identified a barrel/bullet/crown combination that really flies so much flatter than computer models predict, he could bottle it, sell it and be an instant millionaire.

Good then we agree he didn't say how long the bullet was yawing

Regardless, the point is that believing such crude and inaccurate measurement methods are sufficient to prove some radical theory that his particular rifle defies the laws of exterior ballistics is just silly, and it makes me sad so many readers will eat it up.

If that's what you take away from the article then I respect that. Thank goodness that's not what he said.

May I respectfully suggest you read the article again. Because that's exactly what he said. BC's just can't be trusted. If you live the Rockies, your bullet may have a BC 20% higher than advertised (like the example he gives). If computer models can't predict trajectory well enough for you to hit the target at 400 yds, they aren't going to be within 10 feet at 1000 yds! Luckily, that's just not true.

Read it several times. The author never said "that BC's are not all that accurate and that they, along with ballistics software cannot be relied upon to accurately predict trajectory or we should throw out all known exterior ballistic science." If it's there I'd appreciate it if you could tell me the page number and how many paragraphs down.


That was posted on another competing board so I probably shouldn't link. He has actually said much worse than that about long range hunters but wanted to stay out of that.

Not sure what you mean by competing board. Many members here are also members of other forums and link on occassion but if your uncomfortable then send me a PM with the link.

The point was when somebody not only doesn't practice your hobby but holds disdain for it, he might not be the best source of technical information and advice on the subject.

Thanks for responding. I appreciate it and look forward to the PM.

 

[Jon A]

vary any of those and BC changes...that's a fact

No, it's not a fact. It's wrong. He is wrong. You believe him, so you are wrong. That's the point. The damage being done of which I spoke has been done on you. Because you don't understand. Now, let's remedy that:

The standard conditions corrected BC (which is all you should care about) will not change. If you change the conditions, yes, the actual trajectory, etc, will change. This is because the aerodynamic drag on the bullet will change with the conditions. But it will also change on the G1 or G7 "standard projectile," so the relative rate of velocity decay between the two bullets (which is what BC is) will remain constant. The BC did not change. Your conditions did, the BC did not.

You will not be able to find a single ballistics program that will give you accurate results by entering .300 at high altitude for a bullet that has a correct and accurate sea level BC of .250 if you enter the rest of the information in the program correctly. This was the example he gave. He was wrong. If you believe him, you will be wrong.

If that's what you take away from the article then I respect that. Thank goodness that's not what he said.

You're sounding like a broken record here. Pretending he did not say something that he did is no credible defense of what he said. Specifics:

The author never said "that BC's are not all that accurate

Did he or did he not say:

Vary any of those conditions and BC varies as well. Elevation has the biggest effect. The BC of, say, a typcial 55-grain plastic-tipped 22 caliber varmint bullet can increase from .250 at sea level to well over .300 in the rocky Mountains.

I copied that word for word from the article. Please do not respond with "thank goodness he did not say that" because he did. Word for Word. He said it would change. It won't.

along with ballistics software cannot be relied upon to accurately predict trajectory

Did he or did he not say:

the bullet will shoot a lot flatter than indicated in any computer model.

and

This is a lot flatter than any ballistic program suggests, even when higher elevation is plugged into the equation.

Again, if you respond with "thank goodness he did not say that" I'm going to scream. It's copied word for word so he most certainly did.

Does it or does it not say that the computer models will be wrong? If something is consistently wrong, "it cannot be relied upon to accurately predict trajectory," can it?

This of course leads to the conclusion:

The only way to truly find out the long-range trajectory of a particular bullet in your rifle is still to shoot the darn thing.

and

to be realy, truly certain where any bullet will land at a certain range and elevation, you simply must shoot them from your rifle.

Again, if we were talking about 2000 yds or even much more than 1000, one can make a case for that because there truly are so many variables it can be quite difficult to predict the drop correctly on the first round. But he is talking about 400 YDS!

Keep in mind, 400 yds is kindergarten stuff to most here. If you have accurate sea level BC information on your bullet, you don't shoot at 400 yds "to find out" where they will hit. If you know what you are doing you know where they will hit. You shoot them to confirm you know what you are doing and aren't screwing something up somewhere.

There are lots of occasions people have problems predicting bullet drop at 400 yds. Inexperienced people can get these results by making any one of a multitude of mistakes. From using bad BC or velocity information to simply using ballistics programs incorrectly, to ranging errors, to having scopes that don't track or track incorrectly to using the wrong scope height, to using different shooting form for different targets affecting POI, to using a very large (imprecise) group to form some sort of conclusion, etc. The possibilities are nearly infinite.

So when an inexperienced person doesn't get the expected results at only 400 yds, there can be many reasons for it. Any time this happens, jumping to the conclusion that there is some sort of magic happening between his particular bullet and barrel that allows it to fly flatter than a computer model can predict, is guaranteed to be the wrong conclusion. It's always the inexperienced that jump to such incorrect conclusions so quickly.

Most of us here have experienced situations like this--especially when we were first starting out and lacked experience in LR shooting--where the bullets just aren't flying like they are supposed to. Often, we jumped to conclusions like the above because we didn't know any better. Eventually, we usually figured out what it was we were doing wrong and when the mistake is corrected the actual trajectory mates up with what the computer says very well.

So that's why articles like this one do more harm that good. Telling people that even with accurate BC information such as Berger's, one cannot predict trajectory even at only 400 yds is simply wrong. Instead of educating, it is reducing the readers' understanding by giving them false information. This will only make it more difficult for readers to become proficient at long range because their first inclination will be to blame any unpredicted results on some sort of ballistic magic, instead of looking for mistakes in their own technique.

There are a large number of hunters out there who really believe BC's are pretty much made up numbers that don't mean much. And they believe that computer models will only give one a "rough idea" little better than a wild guess at 400 yds. If one never hunts beyond 400 yds, they can get by believing this stuff forever. But this is detrimental to long range shooting and specifically hunting.

When hunting LR, there are so many possible combinations of range, angle, altitude, temperature, etc, it is simply impossible to gather enough data by "shooting and see how far they drop" to cover all possibilities. You would burn out a barrel before filling a data book with enough information to cover every possible combination of conditions you may run into in the field with an identical situation where you actually measured the drop.

This is why knowledge and trust in exterior ballistics is a must for success. You need to be able to compensate for conditions you probably haven't run into on your home range whether that's with a PDA, pre-printed drop charts or even a BDC you will diverge from when corrections are required.

Of course actual shooting is required. But contrary to popular belief, it is not to "find out" what the bullet will do downrange as if that is some sort of mystery (a belief commonly held by "normal" hunters). It's to confirm your information, methods, techniques and equipment are correct and performing properly. When you have some experience under your belt, have accurate BC and velocity information and meticulously pay attention to all the possible little sources of error (measuring scope clicks, etc), you'll find you are rarely surprised by where the bullets land.

When this isn't happening for you at only 400 yds, you need to stop right now! And figure out what it is you're doing wrong because you have no chance of being consistently successful in varying conditions in the field at much longer ranges.

When your information, methods, techniques, and equipment are confirmed as being accurate and reliable by a more modest amount of shooting so you don't ruin your barrel before hunting season even starts (out to ranges as far--or better yet farther--as you would possible try on an animal in the field) under different conditions you can feel confident your corrections for whatever you see in the field will be true--even if you don't have "actual drop data" for those specific conditions.

Without the understanding that BC's really don't change significantly (unless your twist is way wrong or something) and that computer models really can be accurate if you are doing everything right, your success at extended ranges will always be limited.

 

[Eaglet]

Jon A, did you breath while typing that?

Man you almost had me reading it without breathing!

 

[RockyMtnMT]

I've got to say Jon A is right on here. The article basically leads one to believe that bc's are somehow mysterious, and different geographical circumstances make it even harder. Or that you could get lucky and have a rifle like his that shoots flatter than is physically possible.

I don't have a lifetime of long range shooting, but I do shoot and hunt at different temps, and elevations, with predictable results out to 1000yrds.

Just my .02

Steve

 

[MontanaRifleman]

I think the guy was using HATs

 

[Chas1]

vary any of those and BC changes...that's a fact
No, it's not a fact. It's wrong. He is wrong. You believe him, so you are wrong. That's the point. The damage being done of which I spoke has been done on you. Because you don't understand. Now, let's remedy that:

The standard conditions corrected BC (which is all you should care about) will not change. If you change the conditions, yes, the actual trajectory, etc, will change. This is because the aerodynamic drag on the bullet will change with the conditions. But it will also change on the G1 or G7 "standard projectile," so the relative rate of velocity decay between the two bullets (which is what BC is) will remain constant. The BC did not change. Your conditions did, the BC did not.

You will not be able to find a single ballistics program that will give you accurate results by entering .300 at high altitude for a bullet that has a correct and accurate sea level BC of .250 if you enter the rest of the information in the program correctly. This was the example he gave. He was wrong. If you believe him, you will be wrong.

"vary any of those and BC changes...that's a fact. To my question did the author say "vary any of those and BC changes" Your previous post said "Yes that is what he wrote" Are we still in agreement on the fact that that's what the author wrote?

advertised BC's, even if accurate, won't do them any good if they don't live at sea level.
Quote:If that's what you take away from the article then I respect that. Thank goodness that's not what he said.
If that's what you take away from the article then I respect that. Thank goodness that's not what he said.
You're sounding like a broken record here. Pretending he did not say something that he did is no credible defense of what he said. Specifics:

Not sure why you feel the need to insult me. Just for the record I haven't and am not defending anything the author wrote just merely pointing out that the author didn't say "advertised BC's, even if accurate, won't do them any good if they don't live at sea level." You did.


Quote: The author never said "that BC's are not all that accurate

Did he or did he not say:

Quote: Vary any of those conditions and BC varies as well. Elevation has the biggest effect. The BC of, say, a typcial 55-grain plastic-tipped 22 caliber varmint bullet can increase from .250 at sea level to well over .300 in the rocky Mountains.
Vary any of those conditions and BC varies as well. Elevation has the biggest effect. The BC of, say, a typcial 55-grain plastic-tipped 22 caliber varmint bullet can increase from .250 at sea level to well over .300 in the rocky Mountains.
I copied that word for word from the article. Please do not respond with "thank goodness he did not say that" because he did. Word for Word. He said it would change. It won't.

What you copied word for word from the article doesn't show the author saying "that BC's are not all that accurate." just merely pointing out that the author didn't say that. You did.

Quote: along with ballistics software cannot be relied upon to accurately predict trajectory

Did he or did he not say:

Quote: the bullet will shoot a lot flatter than indicated in any computer model.

and

Quote: This is a lot flatter than any ballistic program suggests, even when higher elevation is plugged into the equation.

Again, if you respond with "thank goodness he did not say that" I'm going to scream. It's copied word for word so he most certainly did.

Does it or does it not say that the computer models will be wrong? If something is consistently wrong, "it cannot be relied upon to accurately predict trajectory," can it?

Just merely pointing out that the author didn't say that. "that BC's are not all that accurate and that they, along with ballistics software cannot be relied upon to accurately predict trajectory or we should throw out all known exterior ballistic science." You did.


Jon, I get the impression that you want to debate the validity of the article with me...not sure why as I have no dog in that fight. My only purpose here is to clear up any confusion on what the author wrote (his actual words).

Here's an example: you wrote: He (author) has said elsewhere "no scope used to hunt big game should have any sort of exposed turrets or parallax adjustment."

The author actually wrote: Wny anybody would complicate a serious big game scope with exposed turrets and ANOTHER turret for parallax is beyond my understanding.

By pointing this out one might think I'm drawing some sort of a distinction between the meaning, I'm not...I'm just pointing out that what the author said isn't what you said the author said...that's a fact...while the meaning might be the same to you and I...it may not be the same for someone else.

On a side note for anyone reading this the author on the subject of exposed turrets later went on to say: Obviously, we all tend to state our preferences, and my personal preferences, likes and dislikes come from some experience, not total ignorance of the things you are talking about.

I have killed a lot of varmints out to 900+ yards with a combination of turrets and various reticles, and out to 600 have found that the right reticle will do the job even on prairie dogs--which are a LOT smaller than the vital area on an elk, or even a deer. Have also seen such reticles work far too often on big game at 600 to blithely dismiss them. The "secret" to using them is to actually shoot with them at various ranges. It doesn't matter if they match up "perfectly" with a certain load at 100, 200, 300, etc. yards if the shooter knows which reticle to put where at X range.

What I have also seen quite a bit of in hunting and guiding for big game is exposed turrets being fiddled with, or accidentally turned to the wrong setting. Ihave also seen big, long scopes being knocked out of zero or even bent after a day in saddle scabbards. Some of this was operator error (not mine, since I wasn't using the scopes to hunt big game) but some of it was mechanical. With the exception of Nightforce and maybe one or two others, using a really big scope in hard Rocky Mountain hunting risks it being knocked out of zero by normal mishaps. I have seen this too many times to count.

Another thing I have seen too many times is somebody so obsessed with the relatively small chance of taking a very long shot that they fail to prepare properly for the much more likely shorter shots. Now, obviously some people are prepared for any likely shot--and in my experience a simpler, smaller scope like a 3-10x with the right reticle is a very good choice for that. This not just my personal preference, but an observation resulting from being around lots of hunters in the field.