What am I doing wrong?

[tt123]

When I downloaded Strelok about a year ago, I didn't have access to a chrono. In order to try and work it out, I zeroed at 100m, then shot at 200m and 300m, to see how much drop there was. I then adjusted the velocity in the calculator (I'd already put everything else in), until the amount of drop matched at the distances I'd fired at. I've tried it once or twice on steel at up to 5-600m, and at various distances up to about 250m hunting and it seemed pretty much on target.

Recently though, I had the opportunity to shoot over a chrono, and was surprised to see that my load was about 35 m/s faster than I'd thought.

Putting the new (correct) velocity into Strelok and other calculators give me results that don't match reality.

Obviously something I'm inputting is wrong. Any ideas what?

I'm shooting Hornady .308 165gr SST (advertised BC of .447) at about 815 m/s. My scope is 4.7cm above the axis of the bore. I've been shooting at sea level, and at about 5-12 degrees C.

Any ideas?

tt123

 

[Lowlight]

Screenshots of your App would help...

But the Apps only know what you tell it, and cannot account for the Human Factor. The muzzle difference is pretty common with many of these Apps.

At the end of the day, the App has to match reality as you cannot make reality fit your app. So the way you did it the first time is correct, so don't bother trying it other ways.

Adjusting Muzzle Velocity and BC is how you true it up in most cases, so the modifications to your actual data are to be expected. Plus not all Chronographs are created equal, errors are possible.

Don't get wrapped around the axle, just line up the App to your actual shots on target and move on down the road.

 

[tt123]

Thanks for the reply. Glad to hear that I was doing it right to start with!

I'll keep gathering data, and fine-tuning what I input into the app. It might be interesting to try another chrono too.