Same velocity, same b.c., but heavier bullet = less wind drift?

[codyadams]

Many here may already have heard of, or even experienced this, but for those that haven't, here is the concept:

You have a 7mm, 180 grain Berger vld, with a .345 G7 bc, being sent at 3000 feet per second. On the other hand, you have a .338 cal, 250 grain Berger hybrid, with a .342 G7 bc, also being sent at 3000 feet per second. Lets also say they are both being fired from 9" twist barrels. For all intents and purposes, drop and drift for the two should be essentially identical, or very very close. You have even confirmed drops, and observed drops on both seem to match up with their prescribed bc. However, when out shooting these two guns side by side, at 1100 yards in a 12 mph wind, you observe significantly less wind drift with the .338 cal than the 7mm. What gives?

I personally haven't experienced this yet, maybe because I haven't been in a situation comparing such ballistically similar guns, however I have heard from a few people now, that are much more experienced than I, that state they have seen this, and I believe them. I think it could be interesting to flesh out this subject, and maybe get more from those of you that have seen it. I have heard of this as something that can be a benefit, however personally, this concept is somewhat concerning, mainly for the following reason.


If we strive to improve our long range shooting ability, than we MUST focus on being good at judging wind (especially those of us out west). Going out and shooting on those days that are gusting up to 30 mph, with sustained 15-20 mph winds, trying to go off of what your seeing, feeling, and hearing to time your shots, and get good impacts at range, is a challenge that helps us to get better. The same as shooting in canyons, and figuring out how multiple wind channels effect your shot, all help to learn how to make a good wind call. However, what good is all this work and time in the field if the bullet doesn't perform how our ballistics predict it will? If we are taking a 850 yard shot, and estimate our wind at 14 mph, and because of all our practice we are spot on with the wind call, and we dope/hold 4 MOA for wind, because that is what our ballistics say it should drift, however the 250 grain bullet only drifts 3 MOA......if our target is something the size of a pronghorn, possibly quartering, we possibly now have a problem, either a nasty gut shot, or a very far forward/grazing/or possibly missed shot.

This could especially be a problem if our main practice guns are smaller in caliber, I personally practice with my .260 AI more than my 30 nosler, for obvious reasons. My .260 ai is a 156 berger with a G7 of .334 @ 2940, and my 30 nosler is a 208 Berger with a G7 of .370 @ 2980, so a little better, but similar. I generally confirm my estimates on wind, based on if my bullet hits where I intend it do. If I estimate for a 8 mph wind, hold the prescribed amount, and hit, I know I did it correct. However if I miss, I change my hold to make the impact, then look at what I had to hold to make the hit, to determine what the wind must have been over the course of the bullets flight to give it that much deflection. This creates experience, all my observations of the wind for that shot to impact tell me it was going at X speed. So if another bullet in a bigger, heavier .30 or .338 cal doesn't match up with prescribed drifts, because it drifts LESS, while this may initially appear as a good thing, in my mind, it is inconsistent, which is the enemy of long range shooting.

Hopefully I can get out some time with a few of my rifles side by side and compare ballistically similar rifles in similar conditions and see what I observe. However, what does the community think about this topic? Who all has observed it? What are some of the other pros/cons about this concept? Any theories as to why it could occur?

 

[FURMAN]

Many here may already have heard of, or even experienced this, but for those that haven't, here is the concept:

You have a 7mm, 180 grain Berger vld, with a .345 G7 bc, being sent at 3000 feet per second. On the other hand, you have a .338 cal, 250 grain Berger hybrid, with a .342 G7 bc, also being sent at 3000 feet per second. Lets also say they are both being fired from 9" twist barrels. For all intents and purposes, drop and drift for the two should be essentially identical, or very very close. You have even confirmed drops, and observed drops on both seem to match up with their prescribed bc. However, when out shooting these two guns side by side, at 1100 yards in a 12 mph wind, you observe significantly less wind drift with the .338 cal than the 7mm. What gives?

I personally haven't experienced this yet, maybe because I haven't been in a situation comparing such ballistically similar guns, however I have heard from a few people now, that are much more experienced than I, that state they have seen this, and I believe them. I think it could be interesting to flesh out this subject, and maybe get more from those of you that have seen it. I have heard of this as something that can be a benefit, however personally, this concept is somewhat concerning, mainly for the following reason.


If we strive to improve our long range shooting ability, than we MUST focus on being good at judging wind (especially those of us out west). Going out and shooting on those days that are gusting up to 30 mph, with sustained 15-20 mph winds, trying to go off of what your seeing, feeling, and hearing to time your shots, and get good impacts at range, is a challenge that helps us to get better. The same as shooting in canyons, and figuring out how multiple wind channels effect your shot, all help to learn how to make a good wind call. However, what good is all this work and time in the field if the bullet doesn't perform how our ballistics predict it will? If we are taking a 850 yard shot, and estimate our wind at 14 mph, and because of all our practice we are spot on with the wind call, and we dope/hold 4 MOA for wind, because that is what our ballistics say it should drift, however the 250 grain bullet only drifts 3 MOA......if our target is something the size of a pronghorn, possibly quartering, we possibly now have a problem, either a nasty gut shot, or a very far forward/grazing/or possibly missed shot.

This could especially be a problem if our main practice guns are smaller in caliber, I personally practice with my .260 AI more than my 30 nosler, for obvious reasons. My .260 ai is a 156 berger with a G7 of .334 @ 2940, and my 30 nosler is a 208 Berger with a G7 of .370 @ 2980, so a little better, but similar. I generally confirm my estimates on wind, based on if my bullet hits where I intend it do. If I estimate for a 8 mph wind, hold the prescribed amount, and hit, I know I did it correct. However if I miss, I change my hold to make the impact, then look at what I had to hold to make the hit, to determine what the wind must have been over the course of the bullets flight to give it that much deflection. This creates experience, all my observations of the wind for that shot to impact tell me it was going at X speed. So if another bullet in a bigger, heavier .30 or .338 cal doesn't match up with prescribed drifts, because it drifts LESS, while this may initially appear as a good thing, in my mind, it is inconsistent, which is the enemy of long range shooting.

Hopefully I can get out some time with a few of my rifles side by side and compare ballistically similar rifles in similar conditions and see what I observe. However, what does the community think about this topic? Who all has observed it? What are some of the other pros/cons about this concept? Any theories as to why it could occur?

I have seen the same things Alex speaks of and have for a long time. At first, I thought it was my poor wind reading skills then I started shooting rifles side by side with identical drops and wind calls, but the smaller bullets drifted more. Then I started paying more attention and putting said rifles side by side and seeing it in every instance.

 

[codyadams]

I have seen the same things Alex speaks of and have for a long time. At first, I thought it was my poor wind reading skills then I started shooting rifles side by side with identical drops and wind calls, but the smaller bullets drifted more. Then I started paying more attention and putting said rifles side by side and seeing it in every instance.

How do you personally navigate making good hits on higher wind/longer distance shots when the bullet doesn't drift as much as calculated data says? Obviously you have your experience with it, so I'm sure that helps, but have you documented data with how much deflection from predicted drifts there typically is in different wind amounts? Say, 10, 15, 20 mph and so on? And for weight, 140-160 range, 180-200 range, 200-220 range, what have been your observations?

It almost makes me wonder if this is something that could be profiled bullet by bullet the way applied ballistics does with their drop data, but also apply it to drift, instead of just using the bc model. Or are ab's custom profiles already accounting for wind drift in the same manner?

 

[FURMAN]

How do you personally navigate making good hits on higher wind/longer distance shots when the bullet doesn't drift as much as calculated data says? Obviously you have your experience with it, so I'm sure that helps, but have you documented data with how much deflection from predicted drifts there typically is in different wind amounts? Say, 10, 15, 20 mph and so on? And for weight, 140-160 range, 180-200 range, 200-220 range, what have been your observations?

It almost makes me wonder if this is something that could be profiled bullet by bullet the way applied ballistics does with their drop data, but also apply it to drift, instead of just using the bc model. Or are ab's custom profiles already accounting for wind drift in the same manner?

I don't have it nailed down yet. I don't think it is bad enough under 10mph from 90 or 270 to worry about but as the speed picks up it gets more unpredictable. I have not spoken much about it because I don't have a great solution. I had high hopes for Hornady 4DOF but it is wrong on inline/decline shots when they get steep. Right now everything feels like a trade off.

 

[benchracer]

I have observed this phenomenon myself. I don't have hard data, just anecdotal information to go on. Around Labor Day, a friend of mine and I were doing some shooting at 500 yards. I was shooting Berger 185 Classic Hunters @ 2750 from my .308 Win. He was shooting 300 SGK's @ 2600ish from his 376 Steyr. On paper, the 376 Steyr load should behave very similarly to the classic 175 SMK match loads in a .308 Win.

Winds were 15 to 20 mph, full value. The Steyr was shooting well inside my .308 Win loads when we were making our wind calls. For reasons outside the subject of this discussion, the scope mounted on the Steyr was equipped with a Xmas Tree type BDC reticle calibrated for 6.5 Creedmoor. Interestingly, the wind drift markings @ 500 seemed to sync pretty closely with the 300 SGK load. My friend was consistently center punching our steel targets @ 500 yards, in high cross winds, using 6.5 Creedmoor holds for a load that SHOULD drift like a .308 Win match load that is not well known for bucking wind, while I was having trouble staying on the target with a faster, higher bc load in the same winds.

The only thing that made sense to me at the time was that the heavier bullet was simply more resistant to wind drift.

 

[LRshooterofNH]

Tagging in. Very interesting discussion

 

[Broz]

I have seen it for years. And got called out on it by a well known ballistician. But real world results in testing prove it is real. The latest case was with my 6.5 PRC with a 156 @ just over 3K and my 300 Win Mag+P with a 215 Just over 3K. The bullet are very close in BC. But shooting them side by side in like conditions the 300 has less wind drift. Alex and I have comparred notes on this too and our actual field experience on this topic is the same.

 

[LRshooterofNH]

I'm going to test this theory. My father has a 22-250 AI that pushes a 95 smk at around 3200 fps. I'd like to test this against my 6mm creedmoor with a 109 berger @ 3070 fps. In theory, that 95 smk should have a better bc and drift less pushed at that velocity over my 109. Or I could go up to my 6.5 creedmoor and run a 130.

 

[Broz]

I'm going to test this theory. My father has a 22-250 AI that pushes a 95 smk at around 3200 fps. I'd like to test this against my 6mm creedmoor with a 109 berger @ 3070 fps. In theory, that 95 smk should have a better bc and drift less pushed at that velocity over my 109. Or I could go up to my 6.5 creedmoor and run a 130.

It would be interesting to see the results but the weight difference between a 95 gr and a 109 gr may not be enough to show definite results. The instances we see are of bullet 50 gr plus difference in weight and are at the same velocity with BC's that are very close to each other.

I will add the best test results are shot into groups at 1000 yards plus on paper or steel. Two shooters taking turns with each shot for group adds some credibility as well.

 

[LRshooterofNH]

It would be interesting to see the results but the weight difference between a 95 gr and a 109 gr may not be enough to show definite results. The instances we see are of bullet 50 gr plus difference in weight and are at the same velocity with BC's that are very close to each other.

I will add the best test results are shot into groups at 1000 yards plus on paper or steel. Two shooters taking turns with each shot for group adds some credibility as well.

Yeah I kinda got to thinking that after I posted lol. I could do my 7mm rem mag with the 180 eld-m vs his 300 winmag with the 212 eld-x as well. In theory, my 180 at 3019 fps vs his 212 at about 2950 the 180 should spank that 212 if the bc theory is true. If it's weight the should be pretty equal. Then again we're running into the same issue with not alot of weight difference. I'm going to put some thought into this.

 

[Mark Dille]

I really like this thread. I don't have the ability to test the above, but for those that are planning on a test, is there any way to include two rifles shooting the same load but with a different twist rate as well? So, not only a different caliber, but different twist within caliber/cartridge. This will assess both potential phenomena.

As a side note, I was speaking a few months back with a person in north Texas that teaches long range shooting on his property. One of the things he noticed shooting one day with a friend was that his wind drift was different than his. They were both shooting the same exact bullet out of the same cartridge, twist, etc. His buddy's drift was less, right to left. The only difference was that his buddy was shooting factory ammo, and he was shooting the same bullet, but in hand loads. He grabbed one of the factory ammo cartridges and fired it with the same wind drift his buddy was experiencing. After analyzing it further, he discovered the factory round actually had a cannelure in the bullet and that what he was actually experiencing was additional spin drift from the ribs in that particular bullet, and in the original scenario, the additional spin drift was countering the wind more.

 

[Broz]

The more you shoot, at least here in Montana across canyons or drainages the more you get a seat of the pants feel for what you need for wind. When I consider a rifle build I still look for ways to create a combo that has less wind drift. The narrower the wind drift is the easier it is to stay inside the window.

Another thing I often do is look at wind drift for the shot with two wind speeds. The low and the high. This is easy and quick on my Revic BR4. Punch in the low and lefts say it is 2 moa then the high and lets say it is 3 moa. I will often split it and go by dialing 2.5 moa. If I am off .5 moa either direction I should still be good to 1K to stay in a kill zone.

 

[LRshooterofNH]

Another way to do this rest would be to take a low bc hunting bullet and a high bc match bullet of similar weight fired from the same gun, at the same speed. Drop would obviously be different, but if weight is the deciding factor for wind drift, then in theory they should drift the same.

 

[Broz]

I always tested it with rifles that shoot very accurately and are dialed in to my ballistic solver. If the rifles will not shoot at least .5 moa at distance results could be in conclusive.

So what I recommend for a test is two rifles dialed in, one of smaller caliber and one of larger caliber where bullets weights are quite a bit different but velocity and BC's are very close to the same.

The two shooters would be ideal. Dial the elevation and suggested wind drift into both scopes. The alternate shots at large target at a distance over 800 yards anyway. Both could use the same aim point if calibers are far enough to detect which is which. Or coloring one shooters bullets with a colored sharpie and using paper targets would work too. Or there could be two targets side by side. I would shoot 3, wait 20 minutes for cool down, then shoot another 3. All assuming the wind is constant. This test would be best performed in a flat area where terrain has less influence on wind and wind speeds should be more consistent.

 

[Petey308]

I know I’ve asked Bryan Litz about it a few times because I’ve wondered too, and every time he assures me there’s more to it than appears and that BC and CDMs drive time of flight, which drives both drop and wind drift.

I get it though, when you’re seeing something they doesn’t seem to be reflecting what the experts tell us, you really start to question it. I’m not convinced one way or the other at this point, just adding that I’ve wondered too and consulted Litz personally about it a few times now, because I continue to question it lol.

 

[Petey308]

I really like this thread. I don't have the ability to test the above, but for those that are planning on a test, is there any way to include two rifles shooting the same load but with a different twist rate as well? So, not only a different caliber, but different twist within caliber/cartridge. This will assess both potential phenomena.

As a side note, I was speaking a few months back with a person in north Texas that teaches long range shooting on his property. One of the things he noticed shooting one day with a friend was that his wind drift was different than his. They were both shooting the same exact bullet out of the same cartridge, twist, etc. His buddy's drift was less, right to left. The only difference was that his buddy was shooting factory ammo, and he was shooting the same bullet, but in hand loads. He grabbed one of the factory ammo cartridges and fired it with the same wind drift his buddy was experiencing. After analyzing it further, he discovered the factory round actually had a cannelure in the bullet and that what he was actually experiencing was additional spin drift from the ribs in that particular bullet, and in the original scenario, the additional spin drift was countering the wind more.

I wonder if the cannelure is creating enough parasitic drag that the trued BC is lower, and thus retained velocity is lower and time of flight is higher, and wind drift is also higher.

Spin drift might have an affect too, but not sure about that one.

 

[LRshooterofNH]

I know I’ve asked Bryan Litz about it a few times because I’ve wondered too, and every time he assures me there’s more to it than appears and that BC and CDMs drive time of flight, which drives both drop and wind drift.

I get it though, when you’re seeing something they doesn’t seem to be reflecting what the experts tell us, you really start to question it. I’m not convinced one way or the other at this point, just adding that I’ve wondered too and consulted Litz personally about it a few times now, because I continue to question it lol.

I was thinking this also. The less TOF, one would think less influenced by the wind to a certain extent.

 

[Petey308]

Trued BC likely plays a part. So twist rate and actual stability rate I would think factors in.

Aerodynamics is a complex thing lol. I took an aerodynamics class in college for a pilot’s degree program and it was very hard to keep up lol

 

[LRshooterofNH]

Trued BC likely plays a part. So twist rate and actual stability rate I would think factors in.

Aerodynamics is a complex thing lol. I took an aerodynamics class in college for a pilot’s degree program and it was very hard to keep up lol

Man now I'm really wondering lol. I'm going to do my best to test this out. Only issue is I don't have the wind the guys out west do. And usually when you do get a area here in NH where you can shoot far enough to test this then it's a long narrow cut so the wind is usually in your face or your back.

 

[Broz]

I know I’ve asked Bryan Litz about it a few times because I’ve wondered too, and every time he assures me there’s more to it than appears and that BC and CDMs drive time of flight, which drives both drop and wind drift.

I get it though, when you’re seeing something they doesn’t seem to be reflecting what the experts tell us, you really start to question it. I’m not convinced one way or the other at this point, just adding that I’ve wondered too and consulted Litz personally about it a few times now, because I continue to question it lol.

I was told the same. So I accepted it for a while. But when you see it repeat in field conditions you need to accept that it is real. It would not be the first time my real world experiences differ with things Bryan says are gospel. So I go with what is right there in front of me. Bryan is a very smart man. But I already know who kills the most game at long range on first round kills. So I go with what gets me the hits.

 

[Petey308]

I was told the same. So I accepted it for a while. But when you see it repeat in field conditions you need to accept that it is real. It would not be the first time my real world experiences differ with things Bryan says are gospel. So I go with what is right there in front of me. Bryan is a very smart man. But I already know who kills the most game at long range on first round kills. So I go with what gets me the hits.

100% agree. I like to consult him, but at the end of the day, he’s not the expert I consult for things hunting related. I’ll trust your experience first. This is why I continue to question what he’s told me too, and why I’ve asked him more than once about it, and why I’m still searching for the answer as well. I believe you guys and have no reason not to and it makes it just that much more of a mystery lol.

I’d love to get to the bottom of it lol.

 

[Mark Dille]

I wonder if the cannelure is creating enough parasitic drag that the trued BC is lower, and thus retained velocity is lower and time of flight is higher, and wind drift is also higher.

Spin drift might have an affect too, but not sure about that one.

Well, I should have mentioned drops remained the same. Both were at the same relative muzzle velocity. All the change was only in spin drift. Everything else calculated the same once the spin drift was adjusted up in the ballistic solver.

 

[Petey308]

Well, I should have mentioned drops remained the same. Both were at the same relative muzzle velocity. All the change was only in spin drift. Everything else calculated the same once the spin drift was adjusted up in the ballistic solver.

Well that kind of changes my theory then lol, because if it was drag affecting BC and TOF, drop should also be affected. As I was lol

 

[Broz]

I will leave the other thing that Bryan and I disagree on for another thread. But Alex wheeler is testing one now that may once again prove what we have seen repeat in real life. IYKYK. lol

 

[Gord0]

I would think that it should be a calculable result? You would need a ballistic coefficient of the side profile of the projectile though, which we don't have. Maybe the government has enough $ to set up a wind tunnel with full value wind the entire length at precise speeds... The idea of two shooters swapping guns and firing at the exact same time is the best bet we have for any sort of good data though. The other issue is it wouldn't be a linear result. As the bullet velocity slowed and wind was allowed to act on it for more time the difference would increase exponentially. Same as regular bullet drop.

 

[Trollswatter]

I am not sure how you could accurately come to any conclusion on this unless you were in a controlled environment (some sort of wind tunnel). There are too many variables in a natural environment.

 

[Broz]

I am not sure how you could accurately come to any conclusion on this unless you were in a controlled environment (some sort of wind tunnel). There are too many variables in a natural environment.

You are right. But repeating the test, while alternating shots from the two rifle will produce two groups. If you have two groups around 5" in size at 1000 yards and one is left or right of the other, and you get repeated results, you then have a choice. You can either believe the field results or you can believe the figures on paper.

 

[Trollswatter]

I believe the field results I just don't know how a wind drift number similar to BC without being in a controlled environment. In my simple mind TOF, bullet side profile, weight, barrel twist will all change the wind drift calculation. I agree that a single BC number cannot calculate drop and drift.

 

[Broz]

If you have tight enough groups at same distance , shot from the two rifles in question with and it repeats over and over, I think the shear number of data samples offers the credibility. The tight groups indicate accuracy and credibility and they were shot alternating rifles at the same time I believe it is something we can adjust for.

Just my thoughts and opinion.

 

[Trollswatter]

If you have tight enough groups at same distance , shot from the two rifles in question with and it repeats over and over, I think the shear number of data samples offers the credibility. The tight groups indicate accuracy and credibility and they were shot alternating rifles at the same time I believe it is something we can adjust for.

Just my thoughts and opinion.

I may not be expressing myself well but I agree with everything you are saying. I have never understood how one number on a box can give you accurate information in both directions. The variables are not the same. I just believe for them to print an accurate number on a box to compensate for windage it would need to be tested in a controlled environment.

 

[Broz]

I may not be expressing myself well but I agree with everything you are saying. I have never understood how one number on a box can give you accurate information in both directions. The variables are not the same. I just believe for them to print an accurate number on a box to compensate for windage it would need to be tested in a controlled environment.

I agree, and I am not trying to debate it. I am only stating what we see.

Now if we just had a 1000 yard tunnel with a constant 10 mph crosswind.

 

[FURMAN]

I am not going to read every post but I can assure you Brian does not have everything figured out. Google his current thoughts on positive compensation. I completely understand causation is not correlation but after seeing the exact same repeatable things thousands of times I don't need science to explain wether or not it does or does not happen. It happens. One day someone will get the wind calculators right.

 

[FURMAN]

The answer may be two bcs but they are just coefficients after all. I am guessing the issue will be solved in calculators not a new bc. I may need to play with Hornady 4dof more but like I said I tested it to the point angled shots were repeated and reliably off from other calculators and the other calculators were putting bullets on target when the Hornady was not.

 

[Gord0]

I agree, and I am not trying to debate it. I am only stating what we see.

Now if we just had a 1000 yard tunnel with a constant 10 mph crosswind.

Like I said up in my post, maybe the government has the $ to do the testing 🤣. One day maybe bullet companies will do it. They all have tunnels, add some environmentals to those!

 

[Petey308]

Please don’t take this the wrong way guys, because I’m not insinuating anything, I’m just trying to search for answers in this discussion too. I apologize in advance if I insult anyone’s intelligence or experience.

Has spin drift, coriolis effect, magnus effect, stability rate, properly trued BC, varying winds along the bullet path, etc all been taken into account and corrected/adjusted for too?

I’m not disputing this as being a thing, I’ve just not experienced it as much as some of you, or at least not to the point I didn’t just assume I made a wind call that was off.

 

[LRshooterofNH]

So if it's not related to bc, but weight, what do you use to calculate your wind?

 

[Petey308]

Like I said up in my post, maybe the government has the $ to do the testing 🤣. One day maybe bullet companies will do it. They all have tunnels, add some environmentals to those!

I’ll tell Tommy Todd to get on it over at Sierra lol

 

[FURMAN]

Please don’t take this the wrong way guys, because I’m not insinuating anything, I’m just trying to search for answers in this discussion too. I apologize in advance if I insult anyone’s intelligence or experience.

Has spin drift, coriolis effect, magnus effect, stability rate, properly trued BC, varying winds along the bullet path, etc all been taken into account and corrected/adjusted for too?

I’m not disputing this as being a thing, I’ve just not experienced it as much as some of you, or at least not to the point I didn’t just assume I made a wind call that was off.

When two rifles are shot side by side the simple answer is yes. Berger bcs have not been off for me in any testing done with velocities from a LR or Magneto speed. We are not talking about one or two shooting evolutions. We are also not talking about unvetted rifle/load combos.

I am also not talking about 3-500 yards and in 5mph winds. I am taking about 700,800 etc in 15mph, 20mph winds. I know guys who see it in Fclass were hundreds of thousands of shots are recorded but can not speak to all the conditions.

 

[Broz]

Please don’t take this the wrong way guys, because I’m not insinuating anything, I’m just trying to search for answers in this discussion too. I apologize in advance if I insult anyone’s intelligence or experience.

Has spin drift, coriolis effect, magnus effect, stability rate, properly trued BC, varying winds along the bullet path, etc all been taken into account and corrected/adjusted for too?

I’m not disputing this as being a thing, I’ve just not experienced it as much as some of you, or at least not to the point I didn’t just assume I made a wind call that was off.

My Revic BR4 accounts for all things mentioned as soon as I engage a wind vector and speed.

 

[FURMAN]

So if it's not related to bc, but weight, what do you use to calculate your wind?

I am not sure who you are asking and I am not sure what you are truly wanting to know. A ballistic coefficient is just another coefficient. It is absolutely worthless without a front end calculator to use it to give a known outcome. You can reverse engineer them but then you are assuming your calculator as well as all other inputs are correct.

 

[Petey308]

When two rifles are shot side by side the simple answer is yes. Berger bcs have not been off for me in any testing done with velocities from a LR or Magneto speed. We are not talking about one or two shooting evolutions. We are also not talking about unvetted rifle/load combos.

Yes, I understand that. I’m just trying to come up with talking points and see if there’s anything worth pondering minus coming up with a new way to calculate wind drift, and if that’s the only solution, I’m curious how to develop that. Sounds like we’d all benefit.

 

[Trollswatter]

So if it's not related to bc, but weight, what do you use to calculate your wind?

I think it is related to BC but BC is only part of the equation.

 

[Broz]

Yes, I understand that. I’m just trying to come up with talking points and see if there’s anything worth pondering minus coming up with a new way to calculate wind drift, and if that’s the only solution, I’m curious how to develop that. Sounds like we’d all benefit.

Well the best part of it is all you need to know is which rifle is following the solvers suggestion. And how much you need to deduct from the solution for the rifle with heavier bullets that have less drift. That is why we shoot thousands of rounds each year and why find these things. There is no replacement for practice and notes.

Now when we are talking about this. I am not referring to a 6mm to a 6.5 with just a little heavier bullet. I am talking about a high BC pea shooter, like my 25 PRC , 6mm Creed, or 6.5 PRC compared to one of my big 30's or 338's. When you own 30's and 338's that run bullets from 215 to 230 to 245 to 300 grain at speeds approaching 3200 fps. Or my 375 sending 400 grainers at 3177 fps. you now have rifles that can compare to the smaller hot rods with their heavy for caliber high BC bullets and show them how it is done. This is where we see this with more margin.