Lying to my ballistic calculators

[Joeydias3]

I’m shooting a Barnes 112 match burner in my 6 Creed. I have to fudge the numbers by a lot in my calculators to get the trajectory curve to line up. I’m running Strelok Pro, Ballistics AE and Hornady 4dof. For example, I have to input my sight height at 2.5” when it’s actually 1.9”. I have to adjust the advertised BC of .624 to .640, then things are close. With out tweaking numbers, at 500 yards it calls for 7.5 moa. To get a center line hit at 500 the actual adjustment is 6.5 moa. This load has an average mv of 3078, but it’s hot. Good Pressure signs in the 93 degree heat. But god damn does it hammer!

Is this a problem?? I know my actual dope for this rifle and load out 1300 yards. And it shoots great. My hand written dope in my book works very well and is accurate.

my guess it’s the Barnes bullets. Not enough Info for them in the programs? I don’t fucking know. Hornady eldm and sierra matchkings are very close right off the bat with all these programs.

 

[pell1203]

You can adjust MV and BC to get things to match more closely. However, I would not be screwing around changing the sight height.

 

[Matches Malone]

Agreed with above. You shouldn’t be messing with bore height and I’d recommend that you chill on the BC truing until after your MV aligns with your 600-900y dope. Then start messing with the bc a at about 1000 and out. You might need two or three BCs for different ranges.

As far as the hot loads.

 

[Joeydias3]

You can adjust MV and BC to get things to match more closely. However, I would not be screwing around changing the sight height.

BC and MV alone will not get it close. The BC needs to be at .950 or some ridiculous amount. Add over a half an inch to the sight height, and it’s very close.

 

[Matches Malone]

I used your ballistic ae and trued your mv using the information that was provided. The correct mv for 6.5 @500y is 3224

That being said, im sure there are other errors in how your using your data. My overall point is, it can be done.

 

[wade2big]

What does it matter what a computer says if you already have solid dope?

 

[2010Ruger]

Have you double checked to make sure your environmental inputs are correct? And what kind of chronograph are you using?

 

[Joeydias3]

I used your ballistic ae and trued your mv using the information that was provided. The correct mv for 6.5 @500y is 3224

That being said, im sure there are other errors in how your using your data. My overall point is, it can be done.

Everything is entered correctly. Eldms, Matchkings and Berger are all very close. I’ve only stumbled across this with the 112 match burner.

 

[Joeydias3]

What does it matter what a computer says if you already have solid dope?

It doesn’t. Just trying to figure out why the match burner is off so much compared to every other bullet I’ve shot.

 

[Joeydias3]

Have you double checked to make sure your environmental inputs are correct? And what kind of chronograph are you using?

Magnetospeed

 

[PAYDIRT]

I haven't had a problem with the Match Burners out to 850.

 

[Jolliec]

What is your SD?

 

[Jolliec]

Kestrel and CDM using your data is 6.95 MOA for me.

 

[Dthomas3523]

There’s nothing wrong with changing the bore/sight height.

Many people do it. It’s along the same lines when some people say “never change MV because it’s a known.”

As long as you’re sure you didn’t make some sort of major error, you change whatever you need to, to make it work.

 

[Dthomas3523]

And the general rule of thumb is MV to 600 and BC after.

 

[DocUSMCRetired]

When using a boat tail bullet you should be using a Custom Drag Model for the most accuracy, otherwise you should be using a G7 BC. When it comes to calibrations you adjust the muzzle velocity when in super sonic range, and the ballistics when shooting into subsonic range. We have a checklist which goes through each item with an education breakdown. Here is a link: https://appliedballisticsllc.com/2019/11/07/firing-solution-checklist/

 

[Joeydias3]

There’s nothing wrong with changing the bore/sight height.

Many people do it. It’s along the same lines when some people say “never change MV because it’s a known.”

As long as you’re sure you didn’t make some sort of major error, you change whatever you need to, to make it work.

I agree. If it works it works. Everything else is entered correctly.

 

[PracticalTactical]

I think the op may need to take a more systematic approach.

I get the impression he's trying to use scope height when he should be using BC and MV.

I've found its good to start by tweaking scope height at close range like 25 to 150 yards. That will confirm the base geometry is correct. After scope height is confirmed, then start with longer range factors and tweak BC and MV if needed. But stop messing with scope height past this point.

I also feel its important not to over react when things don't seem right. Keep track of results at different distances and what settings produced those results. See if the error is the same from day to day, at different times of day. Try and identify if the variance is a ballistic problem or some environmental factor that you may not have taken into consideration.

Also try using two profiles for the same thing. Set the first one to default parameters and mess with a second profile. That way you can compare the two and see if you are getting better or worse as you tweak parameters.

Play the averages over time and try to avoid grasping for immediate gratification. Prove it before you move it kind of thing.

Myself, I've placed four 4 foot coroplast targets out at distances like 400, 500, 650 and 760 yards and shot each one back to back. I've found odd things sometimes where I'm high at 400 and 500 then low at 650 and right on at 760. I have no choice but to attribute the discrepancy to environmentals until confirmed in another shooting session.

 

[Long Range 338]

I agree. If it works it works. Everything else is entered correctly.

There has to be an error somewhere in the software as the data lines up with other bullets (so it appears to be the data related to the Barnes bullet). Are you entering the data in as a custom bullet instead of using the bullet data that comes with the program? Try posting some pics of your data entry and the ballistics solver for us to review, we might see something you don't... Obviously its not stopping you from getting the job done with your real world dope from your datebook - perfect example of why to keep one.

 

[Dthomas3523]

There has to be an error somewhere in the software as the data lines up with other bullets (so it appears to be the data related to the Barnes bullet). Are you entering the data in as a custom bullet instead of using the bullet data that comes with the program? Try posting some pics of your data entry and the ballistics solver for us to review, we might see something you don't... Obviously its not stopping you from getting the job done with your real world dope from your datebook - perfect example of why to keep one.

It’s only a 1moa or .3 mil difference from real world to non trued software.

That’s not indicative of an input error.