Thread: Truing a Ballistic Calculator

Hello

I've cronied my load and zeroed the rifle (at 100M). I've shot it at 300Y and 600Y. I've checked I've got the settings in Stelok right.

But the "corrected" drops in the calculator still don't match up, I think corrected I should be 13 clicks at 300Y but Strelok is saying 16.

Is there a good tutorial I can read or watch on this stuff??

Where did you get your bc figure?

And is your zero spot on?

The BC is from Bryn (Targex projectiles) and I've moved it a wee bit. The rifle is shooting pretty well so the zero is solid. I don't have any "feel" for how exact the calculators are. In the past I've used the one in Quickload, and its plenty close enough when you have sighters . . . .

Chronos are not 100% exact.
I always shoot 3x @ 100, 200, 300, 400 and 500m on a big plywood sheet and get the true drops. Once i got that, I adjust the speed in the App so it matches the true drops. And don't forgot, the click value in the scope might not be exact as well. 1 click should be 1 MIL for example but in reality is 1.1MIL so you need to add that into your App as well.

You feed a program with shit data - shit data comes out

Shit 1.1 mil clicks would be huge lol

Assuming all else in your app is correct, adjust MV until solution matches down range results. Chronos are generally just a start point for refining.

https://youtu.be/XszN7-dBDSQ

Inside 600 adjust velocity. Outside adjust bc.

Originally Posted by mikee

Inside 600 adjust velocity. Outside adjust bc.

Wrong awnser

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Thanks Guys

From an offer I received to check data I'm starting to suspect my chrony (an early Magnetospeed) is out by quite a bit as my 22 drops are up the wop too. More thinking required.

Originally Posted by Tentman

Thanks Guys

From an offer I received to check data I'm starting to suspect my chrony (an early Magnetospeed) is out by quite a bit as my 22 drops are up the wop too. More thinking required.

A perfect zero and a good ballistic calculator will do way more than any chony ever can.
Try applied ballistics and watch their truing video.
Not cheap but the best!

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Just double check your data entry. scope height correct,altitude etc? 100 metre zero but shooting in yards, could be giving output for 300 metres not yards.
What scope are you using? some dial in smoa, not tmoa
Add in a few other factors and being out 3 clicks wouldn't be surprising

Yes - the units conversions do get confusing, I'm zeroing at 100m, but our range is in yards so checks are at 300 and 600 yards. I had to "go back" to a MOA scope.

Originally Posted by andyanimal31

Wrong awnser

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Why?
Please explain

Originally Posted by winaa

Why?
Please explain

A drag model calculated and proven by doppler radar does not get changed. MV is the variable factor not the drag model.

Can adjust velocity, BC, scope height etc to get it to all line up. Scope height is often overlooked, just keep adjusting it until your figures line up. As JaSa said, a big sheet of ply is an excellent way to check it. Place a target near the top, shoot your 100 group, then take it to 200, 300 etc etc. Always using the same target, dont touch your dials. Having to mover your target each 100 gives your rifle time to cool down. Dont worry about conversions, just use your rangefinder in the units of measurement you want to work with and range it each time. Circle each group, take your centre of group and work out your drop. Then somehow, and dont ask are how cos its above my pay grade, you can then put all those numbers in to your app. When I did one of mine, I was using a good scope with .1 mil hash marks. Each time I went up to the target I circled the group and then went back to the bench and used the scope to read off my drop.