Balistic calculator in scopes, or for that matter in general.

[Peashooter]

So my friend got the Himicro Alpex lite, and i just picked up the LRF for my oneleaf NV500 scope.

BUT !

We both run into problems with the damn thing actually working.
We can of course enter all the needed parameters, Checked and triple checked, but outside ( further out ) the zero distance we are both shooting too high VS what the scope suggest.

My friend shoot the 13.43gr KO slugs, and i have been giving the JSB Heavy a spin in lack of Hades pellets.
In my friends case the BC is right there on the tin, but i had to dig a little around in the interweb to find a BC for the JSB pellets ( 0.031 )

I have to admit this is a bit confusing for me, and for my not at all technically inclined M8 more than that.

So we can Zero for 30 M and everything is dandy, but then ranging and shooting to 50 - 55 - 62 M and suddenly our shots land 2 to +5 CM too high.
We have not tried shooting shorter than the zero distance.

PS: We are of course not ranging for something behind our targets, they are all large enough that we are not doing that mistake.
Ands we have verified distances with leupold range finder.

The way i see it my only option are to " tune " the BC until it fit CUZ clearly the scope think my shots drop a lot more than they actually do.


Thoughts ? Hints ?? Wisdom,,,,, much welcome.

 

[Scotchmo]

You said that you verified your distances with a range finder. Did you verify your velocities with a chronograph?

 

[SilentSquirrel]

Also
Check to make certain the measurement you entered for scope height above the barrel is on the money
From center of the bore to center of the forward lens, please.

 

[Peashooter]

Indeed a FX chrono and on my rifle also my FCM ( Franken Chrono Moderator ) with the natechrony steadyshot measuring the speed and my rock steady fire position.

All parameters seem so good to go, thats why i do not get it.

 

[Peashooter]

Okay i will have to admit i put in a BC for the JSB Heavy pellets of 0.028 and it should have been 0.031, so in my case that might be the problem.
But on my friends scope there is for sure not a wrong BC entered unless JSB printed a wrong one on the tin.

Height over barrel ( center 2 center )
Height over sea level ( 65 M ) ( official cartographic source )
Barometric pressure
Air humidity
shot speed
ASO

It should all be correct

Air pressure for instance a average of the range weather stations reading ( yes we have that ) and online sources.

Really trying very hard here to use the correct values for the math going on here.

At these moderate distances we are shooting fairly level too, it is after 60 M our range go up a little, so shooting to the very back you are shooting at a 7-8 deg or so up angle.
If anything the 30 M zero distance might be a little down aim, like a few degrees.

 

[Scotchmo]

Indeed a FX chrono and on my rifle also my FCM ( Franken Chrono Moderator ) with the natechrony steadyshot measuring the speed and my rock steady fire position.

All parameters seem so good to go, thats why i do not get it.

I would put the same data into a different ballistic app. Compare to your scope’s app.

They should both predict approximately the same corrections at all distances. If the other app is correct, but not your scope app, it’s possible that the problem is with the scope app. If neither matches your real world results, it’s likely you are doing something wrong.

 

[Peashooter]

that i could do, but i dont think either scope say how much it is adjusting fir a given distance ranged, it just move the marker to where you should hold.
But of course if it match to the marks on the digital crosshair i should be able to tell what it is the scope suggest.

 

[Coinwa]

These programs are not designed for the extremely close ranges that airguns operate at. It will always take a little tinkering to get digital to align with reality.

Also…. A .003 difference in BC is essentially meaningless to the program, so I seriously doubt that’s the source of your issue.

 

[Peashooter]

Yeah i am not sure changing to that more correct value is going to be better, but will give it a try tomorrow even if weather is helluva bad, and really i should be building on the shot shed instead.
But figure i can " waste " a hour doing that.

Also contemplating zeroing on a further distance to see how the system cope with shorter than zero scenario.