BC Variation bullet to bullet is real, and its a problem.

[DocUSMCRetired]

BC Variation from bullet to bullet in the same box is something that is hard to detect with short range work but the further you try to shoot the more that problem compounds. We have been providing shooters who get PDMs a print out which shows this variation. We will have more on this topic in the future but picking a high quality and consistent bullet will help minimize this problem.

 

[THEIS]

Hi,

At what distances are you measuring and highlighting the variations to/at?

Sincerely,
Theis

 

[brianf]

^^^ plus

was there any sorting or measurements made to the box, or was it received in the mail and loaded

would be nice to know if the box was sorted what sort was most effective etc..

 

[DocUSMCRetired]

Hi,

At what distances are you measuring and highlighting the variations to/at?

Sincerely,
Theis

Depends on the caliber of the bullet. Most of what we tracked for PDMs were to around 850 yards for Rimfire, and to 2K+ for centerfire. We are tracking into subsonic for our data.

 

[DocUSMCRetired]

^^^ plus

was there any sorting or measurements made to the box, or was it received in the mail and loaded

would be nice to know if the box was sorted what sort was most effective etc..

We do not sort a manufacturers bullets. A shooter might, but we do not. We shoot them as they are received. We also purchase most of ours from retail stores to prevent cherry picking. Everything shot this past weekend however was provided by the user.

A lot of what I have gotten to see, manufacturers are pretty consistent when it comes to the manufacturing tolerances. I know that at the PRE even when using different calibers the brands had relatively similar variation.

 

[LastShot300]

Hornady showed the same years before, nothing new here to call Mom about.

 

[DocUSMCRetired]

Hornady showed the same years before, nothing new here to call Mom about.

Years ago Hornady was taking RADAR systems to events. Allowing any attendee to fire their own rifle and ammo systems over it. Uploading that data directly into an app for them to use, and providing print outs of that data to those in attendance to see the data first hand, including the BC variation of that particular bullet shot to shot at 2400 yard targets?

Yeah, no.

 

[brianf]

With the research gathered so far,

has there been any correlation of data giving you a reason

Per Box:

bullet weight variation
bullet tip variation
jacket thickness
etc

thanks

 

[LastShot300]

Years ago Hornady was taking RADAR systems to events. Allowing any attendee to fire their own rifle and ammo systems over it. Uploading that data directly into an app for them to use, and providing print outs of that data to those in attendance to see the data first hand, including the BC variation of that particular bullet shot to shot at 2400 yard targets?

Yeah, no.

Have you read my other post on your radar tours?

On the other hand, my reply was not about what you are doing, since I've addressed specifically the topic at hand which is the BC variation.

 

[Lowlight]

Hence

We have been talking about tweaking BC in the same breath as changing muzzle velocities, in short, we put equal weight on both tweaks to the software. We find tweaking the BC has better long term results, especially when traveling. Doing MV alone creates a lopsided curve that doesn't travel well.

We see the BC as a dynamic number that should be matched to the individuals' system vs using an off the shelf average.

Averages are fine for most, but the tweaks do help.

 

[Rthur]

What percentage variation is being observed?

R

 

[Ledzep]

What performance increase would I be likely to gain from using your service & equipment over 4DOF with an axial form factor tune?

 

[AIAW]

Some comparison data against say a batch of CNC’d solids would be interesting.

 

[LastShot300]

Hence

We have been talking about tweaking BC in the same breath as changing muzzle velocities, in short, we put equal weight on both tweaks to the software. We find tweaking the BC has better long term results, especially when traveling. Doing MV alone creates a lopsided curve that doesn't travel well.

We see the BC as a dynamic number that should be matched to the individuals' system vs using an off the shelf average.

Averages are fine for most, but the tweaks do help.

In the end, you'll always end up with averages because there is no other way. What's important is how much variation a particular bullet shows from a particular barrel. On the other hand, it is of no consequence if dealing with BC or Cd data since one derives from the other, it's as simple as that. Tweaking will always be required for real LR work going transonic and the solver is key to this problem as much as the data itself.

 

[Lowlight]

All software should be banding BCs anyway

Using Stepped values would work better across the board

 

[LastShot300]

All software should be banding BCs anyway

Using Stepped values would work better across the board

For some software stepped BCs are the way to go, for others like CB, FFS or 4DOF with a built-in mechanism to adjust the drag curve I don't think so.

 

[Lowlight]

they need it too

Hornady broke their app with the last update it stopped working correctly as they changed something. During class guys spent hours trying to get the full curve to work, they finally hacked the zero range in order for it to work. 2 weeks prior it was a simple process, after it was not working

Plus Hornady offers banded numbers if you do it manually

Banded BCs have value regardless of the App,

 

[Clearlight]

This confirms exactly what I have seen with particular brands of projectiles. Shooting in the same
conditions on the same day, some projectiles show more vertical than others despite excellent
ES numbers and a consistent shooter. Really stands out over a mile with my 300NM and 338.

For EG; using 225 ELDm's we saw 4+ moa of vertical at 2 k. Despite the mild conditions, we were
thinking ok, theres an updraft or something we are not seeing shooting over two small valleys.
Swapped ammo to the 230 Berger and the vertical disappeared, despite a slightly higher ES.
After scratching my head with AMAX's for years, and seeing Hornady make a big noise about
their new A-Tips, variable bullet BC explains a lot.

I know some guys batch weigh their projectiles and sort base to ogive, for those of us who are
time poor we need to rely on consistent performance within a certain batch number. Lapua,
Berger seem to be the most consistent out of the box. Would be nice to run solids all day but $$$.

 

[LastShot300]

they need it too

Hornady broke their app with the last update it stopped working correctly as they changed something. During class guys spent hours trying to get the full curve to work, they finally hacked the zero range in order for it to work. 2 weeks prior it was a simple process, after it was not working

Plus Hornady offers banded numbers if you do it manually

Banded BCs have value regardless of the App,

I've yet to see any need for stepped BCs when reaching out further transonic and not getting a solution with CB or FFS (which I don't use now) and never needed a banded BC. But I see their value for other packages inlcuding Hornady which is Point Mass with a twist. Wasn't aware of this new glitch with Hornady's. What do you think they did to broke it?

 

[whatsupdoc]

@DocUSMCRetired Have the CNC machined solid bullets BC variation been better than conventional bullets ?

 

[DocUSMCRetired]

With the research gathered so far,

has there been any correlation of data giving you a reason

Per Box:

bullet weight variation
bullet tip variation
jacket thickness
etc

thanks

We do actually have some data for reasoning. We plan to release a couple of articles on this over time.

 

[DocUSMCRetired]

Hence

We have been talking about tweaking BC in the same breath as changing muzzle velocities, in short, we put equal weight on both tweaks to the software. We find tweaking the BC has better long term results, especially when traveling. Doing MV alone creates a lopsided curve that doesn't travel well.

We see the BC as a dynamic number that should be matched to the individuals' system vs using an off the shelf average.

Averages are fine for most, but the tweaks do help.

The better solution is to just not use a BC. No reason for it in this day and age, when you can use actual flight models.

 

[Lowlight]

Agreed,

We just don't have a enough flight data for enough bullets for it to be the only solution

 

[DocUSMCRetired]

What percentage variation is being observed?

R

Depends, some are as low as 1/3rd of a percent. The Berger 215 is a good example of this. It was at around .66%. Which is under the 1% cutoff for a good bullet. The Berger AR 130 Hybrid showed a .34% variation through transonic into subsonic which is very good. However some bullets are as high as nearly 2%. You never want to see over 1% for a decent bullet.

 

[DocUSMCRetired]

Agreed,

We just don't have a enough flight data for enough bullets for it to be the only solution

We have flight data for over 850 bullets. That's a pretty good start.

 

[DocUSMCRetired]

What performance increase would I be likely to gain from using your service & equipment over 4DOF with an axial form factor tune?

Fairly simply put, you would have an exact flight model from your system. At that point the only variable would be your Sight Scale Factor, and your Powder Temp Stability. The Barrett guys were able to get a 1st round hit using this system at 2125 yards, with an employee who had never shot beyond a mile. That was using factory ammunition as well and not hand loads.

 

[DocUSMCRetired]

Some comparison data against say a batch of CNC’d solids would be interesting.

We have this data, and we have found that in this regard lead core bullets perform better.

 

[DocUSMCRetired]

In the end, you'll always end up with averages because there is no other way. What's important is how much variation a particular bullet shows from a particular barrel. On the other hand, it is of no consequence if dealing with BC or Cd data since one derives from the other, it's as simple as that. Tweaking will always be required for real LR work going transonic and the solver is key to this problem as much as the data itself.

This is incorrect. A number of shooters were able to shoot well beyond a mile without any tweaking at all.

 

[DocUSMCRetired]

All software should be banding BCs anyway

Using Stepped values would work better across the board

Banded BCs are a bandaid for systems which are not able to use CDMs/PDMs, use of the actual flight models are a far better method.

 

[DocUSMCRetired]

@DocUSMCRetired Have the CNC machined solid bullets BC variation been better than conventional bullets ?

Lead Core bullets generally have the advantage in this area. However we do have some design features in the new Berger Solids which help to mitigate this.

 

[LoneWolf_052713]

What happens when the next lot of bullets is say .020 shorter to the OGIVE than the previous lot tested. Are you going to need to create an entire new profile? I have seen up to this amount of variation between lots of 140 Hybrids.

 

[DocUSMCRetired]

What happens when the next lot of bullets is say .020 shorter to the OGIVE than the previous lot tested. Are you going to need to create an entire new profile? I have seen up to this amount of variation between lots of 140 Hybrids.

Each time we issue an update we include 3 categories. New Bullets, New PDMs, and Updated bullets. What happens is the system(AB Connect) evaluates the previous lot, and the new lot. Then our server determines if their is enough change to issue an update to the model. This is pretty rare with the Berger's, and we do all of the testing for them.

A couple of things to note here, we do not use hand calipers (which are prone to errors such as how much pressure is used from bullet to bullet measurement) in order to measure dimensions. We use an optical comparitor which can measure to 6 decimal places using an optical microscope. The human is removed from the process. Also the length, while it determines the spin drift, might not have an affect on down range performance. However we do test for this, and then we issue an update if variance is measured. Ouur bullet dimensions you see are measured as well as the performance.

 

[LastShot300]

This is incorrect. A number of shooters were able to shoot well beyond a mile without any tweaking at all.

Yes, is possible, but very uncommon given the realities of such variations in MV, BC, Cd, etc. there is no such thing as a perfect world out there.

 

[DocUSMCRetired]

Yes, is possible, but very uncommon given the realities of such variations in MV, BC, Cd, etc. there is no such thing as a perfect world out there.

I have to disagree. I have worked with tens of thousands of users, and many many of them have experienced good results. I get emails, phone calls, and more on a frequent basis where users are having great success and are looking for that next step up. So I have to disagree with your statement.

 

[THEIS]

We have this data, and we have found that in this regard lead core bullets perform better.

Hi,

So are you saying that lead core bullets have less BC variation than monolithics from Cutting Edge, Flatline, Badlands, etc?

Based off the potential weight variations from projectile to projectile alone, not considering any of the jacket thickness, core off-center, core cavity, etc etc) I am not sure how that can be possible.

So for the sake of data comparison....can you list each projectile weight of a box of lead core projectiles you have for .338 and then list each projectile weight of a box of Flatline .338 you have?

Also..during your BC variation test comparing lead core to monos....is the rifle built with proper aka fast twist rate to achieve the best performance of the monos or are you running the monos through rifle built with standardized twist rates for lead core bullets?

Sincerely,
Theis

 

[AIAW]

We have this data, and we have found that in this regard lead core bullets perform better.

Interesting. That is surprising actually given the piece-to-piece outside precision coupled with the solid core versus a more malleable, “fluid” core. Perhaps the additional ogive-core density (if perfect) is the key with jacketed lead-core versus solids?

You guys have this data published or plan on publishing in the future?

 

[Lowlight]

Ya,

I find it hard to believe as well if you compare apples to apples a monolithic bullet should outperform a jacketed one.

When Hornady tested the gain twist barrels and various twist rates they noticed the slipping of lead under the jacket of traditional bullets, especially overspun like people like to do. Dave Emry described it to me when we spoke about the GT Barrels from Bartlein to a wheel losing a tire weight and throwing the bullet out of square. The lead under the jacket shifts and that movement affects the balance.

We see the jacketed bullet's come apart all the time, especially when pushed hard, so I am not sure how it was compared. I think we have a case of, we don't make them so they don't work going on here.

Bullets are the weak link and solids properly shot should be noticeably different from a jacketed bullet.

 

[THEIS]

Hi,

Based off a random internet picture alone.....there is just no way I can see how a lead core such as this Berger pictured has less BC variation than a mono from a reputable company...

It does not take fancy equipment to see where the variation would be from....

Sincerely,
Theis

 

[LastShot300]

I have to disagree. I have worked with tens of thousands of users, and many many of them have experienced good results. I get emails, phone calls, and more on a frequent basis where users are having great success and are looking for that next step up. So I have to disagree with your statement.

Doc, it's simply impossible to not have such variations in the real world. Granted you may a have a hit or even many at extended distances, but target size rules here though. That is the vital factor to define a "success" and like I wrote before, not saying it's not happening but not on a regular basis for competition size targets, just check the results of the best shooters out there as recorded in a sanctioned competition and it's simply not happening

 

[DocUSMCRetired]

*** Snip ***

Correct, Solid Core bullets show less BC Variation, and we have tons of data that supports this. It comes down to stability issues. It is about more than just spinning them fast. Some of our test barrels are 1:6 and faster. We have tested different rifling designs. We have also tested gain twist barrels. We have also allowed other shooters to test on our system, so we have independent rifle data as well. So it is also not for a lack of test equipment. We do have the proper rifles to drive solids, we have developed a number of solid bullets which are currently in production as well as we do perform independent testing for a number of bullet companies.

***snip***

We do have plans to publish this data in the future.

***snip***

This is an incorrect assumption. We were able to alleviate some of the problems solids have, but lead core bullets currently tend to have far less BC Variation. We are not the only ones who have been seeing this kind of data as well.

We do design and help produce solids, as well as provide independent testing for a number of manufacturers. So the assumption of "I think we have a case of, we don't make them so they don't work going on here. " is a false statement. We do make them, we have a lathe in our lab and can turn new ideas at any time. We also have tested hundreds of bullets from many manufacturers through consultation work and for our library. Some solids currently on the market have as much as 2.7% BC variation, vs lead core counterparts with only around 0.4% variation.

We will be releasing more information on this in the future though, this was simply to get people thinking.

 

[sleeplz]

Doc, what's been your experience on gain twist barrels?

 

[THEIS]

Hi,

@DocUSMCRetired
In case you did not see the question in my previous thread....

So for the sake of data comparison....can you list each projectile weight of a box of lead core projectiles you have for .338 and then list each projectile weight of a box of Flatline .338 you have?

Also...What Infinition doppler system are you guys using for these BC variation test?
BR-29015?

Sincerely,
Theis

 

[Near miss]

Interesting topic..
Sorry for the crapload of questions.
No need to answer them all, some are just to carry the thought process.

So why are the lead core bullets better?

Would lead mono be better than regular materials?
Is it the copper layer then that does it?
Does it matter how thick the copper layer is?
Is it the malleability of lead? If one shot copper jacketed tungsten core (not malleable), would that have an edge over lead cores?

Also, did you draw any fascinating conclusions from your 22LR tests? As they use monolithic bullets.

Did you find any 22LR bullets which stood out from the rest with low BC variability?

 

[DocUSMCRetired]

Hi,

@DocUSMCRetired
In case you did not see the question in my previous thread....



Also...What Infinition doppler system are you guys using for these BC variation test?
BR-29015?

Sincerely,
Theis

We could mark weight variance. But we generally just test the bullets as they are packaged on the shelf and we don't sort. This prevents cherry picked data.

We have multiple radar systems, and different arrays which provide multitudes of data.

 

[DocUSMCRetired]

Doc, what's been your experience on gain twist barrels?

We published that in one of the books, and I know I don't plan to use one right now. Nothing wrong with them.

 

[DocUSMCRetired]

*** snip***

The shorter fatter bullets have improved stability over longer skinny bullets. They are more forgiving is part of it. Bullet design does matter, and so does the jacket design. I was just looking at test results for a lead core bullet which showed 2.5% BC Variation. Also the Berger solids are showing promise and hitting the sub 1% mark. So good bullet designs play a big part.

I don't want to give anything away on the rimfire stuff, but we did find some really good data which we are working into a report. We found some 22LR with just killer ELR results.

 

[Alan Warner]

Doc:
Care to put money where your claims are? I'll split the cost to Dave for his work.
Step up to the plate
Alan

 

[LastShot300]

Also...What Infinition doppler system are you guys using for these BC variation test?
BR-29015?

That's one I've seen in AB photos as well as one MV head unit. This model is basically the same used by several other manufacturers including Hornady and Barnes. Another option is going Weibel.

 

[THEIS]

That's one I've seen in AB photos as well as one MV head unit. This model is basically the same used by several other manufacturers including Hornady and Barnes. Another option is going Weibel.

Hi,

Yep and look at the maximum distance specs of it...Would be pretty hard to validate many projectiles into subsonic distances with it alone.....
Doesn't take much math abilities to extrapolate between the 5.56 and the 155mm to get max distances for other sizes, lolol

Sincerely,
Theis

CALIBER	RANGE PERFORMANCE (TYPICAL / MAXIMUM)
5.56mm (-58dBsm RCS)	> 800m / 1000m
155mm (-25dBsm RCS)	> 6000m / 8600m

 

[LastShot300]

Hi,

Yep and look at the maximum distance specs of it...Would be pretty hard to validate many projectiles into subsonic distances with it alone.....
Doesn't take much math abilities to extrapolate between the 5.56 and the 155mm to get max distances for other sizes, lolol

Sincerely,
Theis

Yup. thought exactly the same the first time I read the specs. If you check some traces out in the subsonic region and beyond the signal to noise ratio is such the scattered data is 100% unreliable to use. So I figure they are just guessing and the reason explaining why "custom curves" are not the ticket for ELR.