MV Chronographs, Calculators and Accuracy

[Chris A Wright]

Curious if anyone out there has experience with error rates at ranges 1000 yards and under on this topic.

If using a chronograph, say a Magnetospeed to determine MV and then putting that data into a calculator, such as Ballistics, Hornady, Applied Ballistics, etc. along with your load data, which results in a Mathematical MV at Transonic Range vs. performing a "truing" process to obtain the same factor.

I am curious if anyone has compared the "App" Calculations with the data obtained via "truing" to see what the margin of error is with the Mathematical calcs.

I ask as I live in an area in where it is very difficult to shoot at Transonic ranges and I am finding inaccuracies with my kestrel readings at yardages under 500 and this is literally the only variable I am unable to nail down.

Any insight would be much appreciated.

 

[Ckleeves]

If all input is dead on accurate and your truly zeroed then I haven't seen a ballistic calculator be very far off at all. Might be worth checking your scope to see if your getting a little error there. If there is any tracking error then you can input that so it's not a big deal.

How far off at 500 is your poi vs what the kestrel is telling you?

 

[Chris A Wright]

POI is Slightly over 2 MOA High following Kestrel Calculation. Now there is one other interesting thing in this equation, which is the BC. I am shooting a 52gr Speer HP, NOT Matchgrade, which has a BC of .163. If I use the Matchgrade BC, which is .23, the elevation adjustments on the Kestrel seem to tighten up a bit.

 

[BrentM]

I rarely have any issues at all. Getting the profile dead on is paramount. Using mag or labradar for mv. Using ab or suggested bc. That has always been dead on for me and those I help.

What messes up impact vs app data is scope error or wind issues. People tend to discount mirage, vertical wind, aerodynamic jump, and of course poor shooter alignment issues.

So for me, I trust my data for normal long range, not elr. Elr deals with factors you don't experience at 1000 or less.

 

[Teri Anne]

Good Morning, I am pretty much old school and have tried some of the ballistic calculators. While maybe getting one, "Into the ball park," so to speak don't expect pinpoint accuracy from any simply mathematical calculations. There are way too many variables affecting a bullet in flight that cannot be accounted for. No matter what you plug in, it will never be exactly the same as actual conditions.

 

[Recon$$]

I have found I usually end up making adjustments at truing range. Not always, but more times than not. Not big adjustments but some fine tuning. If 500 is all you got, make the adjustments in the app and go shoot. MV or BC doesn't have to be "correct" as long as the dopes it gives you are.

 

[chav0_12]

Good Morning, I am pretty much old school and have tried some of the ballistic calculators. While maybe getting one, "Into the ball park," so to speak don't expect pinpoint accuracy from any simply mathematical calculations. There are way too many variables affecting a bullet in flight that cannot be accounted for. No matter what you plug in, it will never be exactly the same as actual conditions.

What can't be accounted for besides shifting wind? I think, based on the reading I've done, the guys at applied ballistics to an extraordinary amount of testing and calling it simple math calculations is probably at least a little bit exaggerated. Everything from the design of Berger's bullets to the applied ballistics calculations is all on purpose and I have to imagine nothing was missed. I know my Kestrel AB is pretty spot on when the data is input correctly.

For the OP, from what I hear, there may be occasion when AB didn't get the BC right on other manufacturers bullets. Play with BC, double check MV, especially if it's a new barrel. You should get a lot closer.

 

[BrentM]

What can't be accounted for besides shifting wind? I think, based on the reading I've done, the guys at applied ballistics to an extraordinary amount of testing and calling it simple math calculations is probably at least a little bit exaggerated. Everything from the design of Berger's bullets to the applied ballistics calculations is all on purpose and I have to imagine nothing was missed. I know my Kestrel AB is pretty spot on when the data is input correctly.

For the OP, from what I hear, there may be occasion when AB didn't get the BC right on other manufacturers bullets. Play with BC, double check MV, especially if it's a new barrel. You should get a lot closer.

Generally it comes from people not understanding how it all works. The math and science are not flawed in any way shape or form. The shooter is the issue and most struggle with atmospheric conditions/external ballistics. Strelock, ab, shooter, jbl, etc are all using tried and true science and math to predict bullet flight and they do it exceptionally well. I would guess only 1% of the shooters validate scope tracking, which can be 1% error fairly easily with high end optics. You can true the drop in the app etc but that is the wrong way to do it. Validate scope tracking and input the error and you're done. As far as understanding the external ballistics piece, I rarely see any one actually study that properly. It's like voodoo to most. The rest of us know it's part of the math and science. Get it wrong, well, the result is pretty obvious.

 

[kgunz11]

Your chrono will give you a MV. Adjust the BC until the data output matches what you see on the target.
BC's posted on boxes are averages, not gospel.

 

[Greyfox]

I run ballistic RF's(BR2,BR4, Sig2400) which match exactly to Ballistic ARC with the same inputs. Given velocity and BC is accurate, and conditions are accounted for, most all my rifles have been very close to dead on to 700-800 yards, frequently to 1200 yards. Worst case, performing BC truing past 800 yards puts me on target. These variations may be due to barrel/bullet dynamics. The most frequent reasons for issues, given inputs are valid, are scope error, zero error, and/or shooter error.
Ballistic calculators have come a long way, and are quite reliable. IMO.

 

[Dragoon300]

I don't trust BC's to be close to correct unless AB has it listed. I use their custom drag models when possible.
They have been very close for me, last weekend I tried a new load in 6.5 PRC at 1000 and 1070 yards. I had run it out to 400 last fall with good results. I had a 100 yard zero, Magnetospeed velocity numbers. 153.5 Berger LRHT projectiles. Kestrel environmental data and the AB custom drag model in the calculation. Nailed a 5" target first round!

 

[BrentM]

I don't trust BC's to be close to correct unless AB has it listed. I use their custom drag models when possible.
They have been very close for me, last weekend I tried a new load in 6.5 PRC at 1000 and 1070 yards. I had run it out to 400 last fall with good results. I had a 100 yard zero, Magnetospeed velocity numbers. 153.5 Berger LRHT projectiles. Kestrel environmental data and the AB custom drag model in the calculation. Nailed a 5" target first round!

I think it depends. AB/Litz uses an average. 4DOF hornday uses a step. Sierra I think does too. I am like you I use litz CDC or published data and compare it to step. In many instances the step system and average work the same. I can run AB vs shooter using a step and get the exact same result. Using leica I use AB data since it doesn't allow steps. I think your advice for newer shooters or people who don't understand the BC component is pretty important. You can really chase your tail 700-1000 for example. What I have found that A Tips generally shoot above their average. Step works pretty well but they have a higher BC then advertised.

 

[Mike Matteson]

Watching

 

[Chris A Wright]

Thanks for all the input on this. Lots of excellent insight here.