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.
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.
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?Hornady showed the same years before, nothing new here to call Mom about.
Have you read my other post on your radar tours?
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.
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.
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?
We do actually have some data for reasoning. We plan to release a couple of articles on this over time.
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.
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.
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.
We have this data, and we have found that in this regard lead core bullets perform better.
This is incorrect. A number of shooters were able to shoot well beyond a mile without any tweaking at all.
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.
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.
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.
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.
Hi,
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?
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
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.
We do have plans to publish this data in the future.
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.
Also...What Infinition doppler system are you guys using for these BC variation test?
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 published that in one of the books, and I know I don't plan to use one right now. Nothing wrong with them.
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.
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,
and look at the maximum distance specs of it...Would be pretty hard to validate many projectiles into subsonic distances with it alone.....| CALIBER | RANGE PERFORMANCE (TYPICAL / MAXIMUM) |
|---|---|
| 5.56mm (-58dBsm RCS) | > 800m / 1000m |
| 155mm (-25dBsm RCS) | > 6000m / 8600m |
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.Hi,
Yep
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
