Ballistic calculators off real life drop. why?

[Grizz1148]

Using 2 diff calculators and identical bullet, bc, velocity, weather etc...

Both say for instance 3.8 moa at 300..

I'm dialing to 4 and still low.

Gun is sighted and calculated in the same weather conditions.

Same thing at 750. Having to dial up 2-3 clicks extra every time, every distance. Any ideas?

In this case it's a 6.5 creed, lapua cases, cci br4, 139 Lapua Scenar at 2782 average. Thanks for any help.

 

[Canhunter35]

If ur having to dial up 3 clicks the same every time ur zero is 3 clicks low

 

[coop2564]

If you have double checked your input data its almost always your speed that's off. Does these apps have drop corrections? If so put in your click adjustments and it will calculate you a new speed for the correction. If it does not then lower your speed by 25fps until it shows your actual drop that you have to dial in. This one sounds like your actual speed is a little lower than you have read.

 

[SilverbulletMAG]

Confirmed velocity and BC to be correct? Incorrect data entered = incorrect data output. That said, Gunwerks has a great video on the tube going over how to verify your data through their online calculator. Worth a watch.

 

[Grizz1148]

Velocity verified with 2 chronos. 1 pro chrono 1 labradar.

Zero is not off.

 

[Creedmoor shooter]

If its consistent then it's either your zero or possibly your scope clicks aren't exactly what they're supposed to be

 

[Grizz1148]

If its consistent then it's either your zero or possibly your scope clicks aren't exactly what they're supposed to be

Scope clicks are all I could think of. Zero is perfect.

 

[Canhunter35]

Scope clicks should be cumulative.
3 clicks low at 300,
3 clicks low at 750,
Clearly not your zero...

Do a tall target test if you think ur scope is tracking off

 

[coop2564]

You using 0.578 for BC? What scope?

 

[Grizz1148]

You using 0.578 for BC? What scope?

.579 bc
Leupold lrp 8.5-25

 

[Barrelnut]

Like others have said, it is probably a velocity adjustment. I would adjust the velocity in the app until the app's results matched the number of clicks you actually have to dial at 750 yards. the closer distances will probably take care of themselves then. Usually the BC in the App is not exactly correct for the lot of bullets you have. Also chronos never exactly match the exact velocity either.
I almost always have to adjust my velocity some to get everything to line up.

Also should always do a tall target test with a long range scope.

 

[bigngreen]

If your of by 300 and all your data is tight, it's your zero, I use a 100 yard zero as a rough in then 300 to dial in the exact zero hight. Most all other things are cumulative, speed, BC and tracking.
If tracking shows up by 4 MOA throw the scope in the dumpster, there is no way you should see a tracking error that large for at least on while rev and even then I'd be surprised.

 

[Tidus56]

Also keep in mind the BC on bullets can be inflated from the manufacture. So always verify your dope and like others are saying change your data in the app to match your real life experience. Then verify again at a farther distance. This works for me anyway.

 

[Mach 1]

I have never in my life had a ballistic calculator be perfect. I use a ballistic calculator to get a good starting point and then shoot and get your data in the real world. I use a ballistic calculator to adjust for aspects of environmental factors but my dopes are always shot and verified and adjusted from the ballistic calculator