Applied Ballistics FAQ

DocUSMCRetired

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I have had quite a lot of common questions during my time with Applied Ballistics. I would like to share some of most common questions and answers, in the hopes that you all will spread them throughout the shooting community. A lot of this will reference the Resource Page: www.abmediaresources.com

Q: Where do I measure from to do a Tall Target Test?
A: From the Turrets.

Q:I have a gain twist barrel, or I plan on getting a gain twist barrel, how do I input this/what twist rate should I get?

A: The important thing with gain twist is that the muzzle exit twist needs to be the twist required to stabilize the bullet (or faster). So as a ballistics program input, if it’s a 1:10-8” gain, you would use is 8.

Q: Should I use a G1 or G7 form factor?
A: You should be using a Custom Drag Model, which is neither a G1 nor a G7. It is actually a representation of the actual bullet model against itself. CDMs (Custom Drag Models) ARE NOT G7 curves or segmented BC’s. However if you are going to use a G1 or G7, use a G1 when it’s a flat base bullet like the 22LR and 40 gr FB Varmint, use a G7 when it’s a boat tailed like the .308 185 gr Juggernaut and .243 105 gr Hybrid.

Q: I am using two different apps, and my firing solution is 1/2/3 moa off, can you help me please?
A: The biggest culprit here comes from 1 of 4 different places.
1. BC: Sometimes users will select to use a G7 BC, or switch BCs but the number doesn't actually change. Make sure you verify not only that you have selected the correct drag standard (G1 or G7), but that it is an appropriate number. If you are running a 6.5 Creedmoor, and have a BC of around 600 yet you have selected G7 form factor, this is incorrect.
2. MV: Sometimes users do not have the correct muzzle velocity input (this can be due to change in weather), but it can also be due to using MV Variation (Or Temp Table) incorrectly. We have detailed information on how to use this feature in the AB Mobile Guide on the resources page www.abmediaresources.com. Your input for fps/degree should be between zero and two; any higher and you’re going to be off.
3. Turret Tracking: This tends to throw people off for a number of reasons. First off, some users don't know to even check this. Remember it’s a mechanic adjustment that is subject not only to wear, but defects. Secondly some users don't know how to input it correctly. If you have the Kestrel, you simply correct your MV for this. You can find out more in the Ballistics Calibration Article on the Resource Page on this. If you are using the AB Mobile app, you are entering a correction FACTOR. Meaning that number is going to multiplied by something. So if you change that 1 to a 0, you are in for a world of hurt. The AB Mobile guide on the resource page tells you how to properly use this number, on top of the turret tracking test document you can download which has the formulas and setup for this test. Both of these can be found on the resource page www.abmediaresources.com
4. Segmented BCs: You should always double check and make sure that the segmented BCs are in order. If they do not follow in order for velocity, it can cause firing solution errors.

Q: How important is inputting zero atmosphere?
A: For a 100 yard zero you DO NOT need to worry about atmospherics. This is for long range zeros (example 300 yards). If you zero at 100 yards, your zero is good for altitudes and conditions.

Q: My zero shows to be XXX yards, and not 100 yards, can you help me fix this?
A: Nothing is wrong here. A phenomenon called Aerodynamic Jump is causing this. When a direct crosswind makes contact with the bullet as it is leaving the barrel, it causes a slight and permanent shift in the trajectory. This can be seen by setting your wind speed to 0 or setting your wind direction to 12 or 6 o'clock. You will see your zero has returned to your zero range. This is covered in full detail in Applied Ballistics for Long Range Shooting 3rd Edition, Chapter 5. https://store.appliedballisticsllc.com/ProductDetails.asp…

Q: I am shooting a plastic tipped bullet, will the stability calculator still work?
A: Yes, the stability calculator is accurate for tipped as well as non-tipped bullets.

Q: My barrel twist rate is lower than the optimum recommended, will this be a problem?
A: No. As long as your SG (Gyroscopic Stability) factor is above 1.05. Note the formula has an accuracy to +/- 0.1 SG. Numbers below 1.05 will lose both Accuracy and BC, and most likely tumble. Numbers between 1.05 and 1.45 will have a lower BC but retain Accuracy. Stability levels above 1.5 will have optimum Accuracy and BC. For every 0.1 SG you drop below 1.5 you will have an average of 3% BC loss. This number is better and worse for certain bullets. But for example, if you calculate out to a 1.3 SG then you can expect an average BC loss of 6%. On the other side, over spinning a bullet is a bit of a myth. So if your barrel twist rate is far faster than recommended, you only need to make sure you account for the added spin drift. Also remember the recommended twist rates are for EVERYONE. So shooters at higher altitude, can get away with slower twist rates. Your DA (Density Altitude) plays a role here.

Q: Can we input our cosign value in to the application instead of degrees?
A: No, the reason we use positive and negative degrees is that our system calculates for both uphill and downhill firing. While they are similar, the solutions are not exact for each scenario. The system also takes in to account the slowing of the bullet. Giving you a more precise solution vs the improved rifleman's rule. For more on this read Chapter 4 of Applied Ballistics for Long Range Shooting 3rd Edition. https://store.appliedballisticsllc.com/ProductDetails.asp…

Q: I bought the app on Android and now have an iPhone (or vice versa) can I switch platforms?
A: No, Google and Apple do not honor purchases made on the others store. We do not have the ability to transfer your purchase from one store to another. Even with all the similarities the apps are actually different. They are different platforms, with different coding.

Q: I have lost my password for Web sync, can you help me recover it?
A: Yes, you can reset passwords here: Applied Ballistics Media - Forgot Password

Q: I have purchased your app on my mobile device before, I now have a new device, or multiple devices, do I have to pay to download it again?
A: No, as long as you login with the original login you bought the app under, it can be installed on multiple devices.

Q: I have the Point Mass Solver that came with the book, how can I get this working on my mobile device?
A: The PM Solver cannot be transferred to a mobile device. It will only run on a PC, or on a Windows Mobile device running an OS similar to Windows 8.1 Mobile.

Q: I am looking at a Kestrel vs the App, which one do you recommend most?
A: We recommend the Kestrel over the use of a Phone. The Kestrel has a better battery life (15+ days with Bluetooth off), is more durable (it even floats), and is not reliable on cell service to gather weather information. So the Kestrel will work off the grid (so will the apps, and some like AB Tac are designed for off the grid use) and give you on demand, real time weather data.


Q: I am looking at the K4 vs the K5 which is better?
A: This is dependent on the shooters needs. The K5 is certainly an upgrade from the K4, however when picking an Elite vs Sportsman or K5 vs K4 shooters have different needs, and we have a guide that helps explain these differences so you can make that decision for yourself: http://www.abmediaresources.com/KestrelComparisonGuide.pdf


Q: If my bullet stability is below 1.5 will the app automatically change my BC?
A: No, but we do have a tool that will calculate this for you, and has a copy paste button so you can simply copy it over, or even test out different rifle setups in different conditions to see the effects: http://www.abmediaresources.com/ABToolbox.htm

Another topic that gets brought up a lot is the ability to shoot the ranges needed to do a Ballistics Calibration. Do note, Ballistics Calibration needs to be done ONLY at long range. More specifically Long Range in regards to the caliber, or Mach 1.2-0.9. Remember this is system dependent. A 22LR leaves the barrel transonic, while a 338 might go transonic at 1 mile. This is in part due to error reporting, but also because of the accuracy of our test data. Bryan Litz takes great care in making sure the data collected is extremely accurate. So if you are using our Custom Drag Model data, and your firing solution is off in the supersonic range (Mach 1.2+) then the culprit is more than likely your muzzle velocity. Note: Custom Drag Models are NOT G7 BCs and are NOT Banded G7 BCs. You cannot accurately re-create the CDM by using banded BCs. While this does apply to the use of G7 & G1 Drag Models, because the averaged G7 BC is good for most velocities in the supersonic range. If your solution is off, at Mach 1.2+ then you need to calibrate your Muzzle Velocity. Keeping in mind, that sometimes the firing solution is correct, and your turrets might not be tracking perfect can also be a culprit here. For more details on this, reference Accuracy and Precision for Long Range Shooting by Bryan Litz, https://store.appliedballisticsllc.com/ProductDetails.asp… and the Ballistics Calibration Article http://www.abmediaresources.com/BallisticCalibration.pdf coupled with the Chronograph Performance Review Article http://www.appliedballisticsllc.com/…/ChronographChapter.pdf both found on the Resource Site www.abmediaresources.com. How to tackle this on the different platforms:
1. AB Mobile App: You will be able to input ranges outside the recommended ranges, however it might cause problems due to both error reporting which is covered in the Ballistic Calibration Article, and the limited distance between points.
2. Kestrel: If you attempt to do a DSF (Drop Scale Factor) at too short a distance, it will not accept multiple inputs. They must be done At Mach 1.2 - 0.9 and slower. If you need to adjust in the supersonic range, use the MV (Muzzle Velocity) Calibration.

Keep in mind, these are not all the questions, just some of the more popular ones, if you have any questions, please feel free to ask, as I am looking to expand this FAQ.
 
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