Making sense of Zero and dialing

U

UndFrm

Sergeant of the Hide
Full Member
Minuteman
Dec 13, 2022
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#1
I am perplexed with this. Still fairly new so perhaps I'm missing something obvious?

6mm Dasher, 30in barrel. I zeroed at 100y Used a free ballistic calculator to get the dial at 500y, showed 9.1 but what was accurate on paper was 8.5
No problem, environment etc affects.

Zeroing temperature was 68F and this was at 13F, if that affects.

300y - calculator showed 3.7, actual was... 0.5 up

What doesn't make sense is how my actual dial is up by only 0.5 at 300y when I zeroed at 100y
I haven't had a chance since then to verify at 100y again, that's my next step. Is there something am I missing or for some reason my zero changed drastically on its own?


Thank you
 
Last edited:
#2
Are you confident in the zero?
Is your scope and your calculator marked/reporting in MRADS and not MOA or vice versa? Are you mixing units is what I’m asking.
What are you using for bullet speed in the calculator?

Your 300 yard dial should be closer to 1 mil but your 500 yard should only be around 3 mils. Or 4.5 and 10 moa.
 
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#3
OREGUN said:
Are you confident in the zero?
Is your scope and your calculator marked/reporting in MRADS and not MOA or vice versa? Are you mixing units is what I’m asking.
What are you using for bullet speed in the calculator?

Your 300 yard dial should be closer to 1 mil but your 500 yard should only be around 3 mils. Or 4.5 and 10 moa.
Click to expand...

Fairly confident in zero.
Verified that the scope and the calculator are both MOA.
For the speed, I have been using an average of 2890fps which I gathered using a chronograph. I do understand that since it's an average and the temp will affect the speed as well, this won't be 100% accurate.
 
#6
UndFrm said:
Almost 600
I did zero it when the round count was 250, but updated the speed in the last approx 200 rounds. Did speed up.
Click to expand...
Then it does seem like there is some parameter off in your calculator. I'd go through the Gravity Ballistics process and find good real DOPE. Once you have good actual information, you can alter your inputs on the calculator to figure it out.
 
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#7
Double check your zero, speed, and verified come-up at 300. Your 9.1/3.7 combo makes sense for a bullet that’s zipping right along…even tweaked to be on at 8.5. The .5 makes no sense at all at 300 yards. You should be up a little over 3 MOA at that distance. Any chance you were mis-dialing or mis-reading your turret?
 
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#9
UndFrm said:
I am perplexed with this. Still fairly new so perhaps I'm missing something obvious?

6mm Dasher, 30in barrel. I zeroed at 100y Used a free ballistic calculator to get the dial at 500y, showed 9.1 but what was accurate on paper was 8.5
No problem, environment etc affects.

Zeroing temperature was 68F and this was at 13F, if that affects.

300y - calculator showed 3.7, actual was... 0.5 up

What doesn't make sense is how my actual dial is up by only 0.5 at 300y when I zeroed at 100y
I haven't had a chance since then to verify at 100y again, that's my next step. Is there something am I missing or for some reason my zero changed drastically on its own?


Thank you
Click to expand...
Maybe look at this??
 
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#10
With all due respect, get out your kestrel and learn yourself something. Temp changes, elevation changes, humidity, atmospheric pressure…none of that makes a 3 MOA difference at 300 yards. Or even a .3 MOA difference. It’s not the temp or any other atmospheric condition.

Or, for that matter, the scope height over bore with any reasonable value.
 
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#11
OREGUN said:
With all due respect, get out your kestrel and learn yourself something. Temp changes, elevation changes, humidity, atmospheric pressure…none of that makes a 3 MOA difference at 300 yards. Or even a .3 MOA difference. It’s not the temp or any other atmospheric condition.

Or, for that matter, the scope height over bore with any reasonable value.
Click to expand...
Yep there's a gross conceptual error in there somewhere
 
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#12
To have
UndFrm said:
I am perplexed with this. Still fairly new so perhaps I'm missing something obvious?

6mm Dasher, 30in barrel. I zeroed at 100y Used a free ballistic calculator to get the dial at 500y, showed 9.1 but what was accurate on paper was 8.5
No problem, environment etc affects.

Zeroing temperature was 68F and this was at 13F, if that affects.

300y - calculator showed 3.7, actual was... 0.5 up

What doesn't make sense is how my actual dial is up by only 0.5 at 300y when I zeroed at 100y
I haven't had a chance since then to verify at 100y again, that's my next step. Is there something am I missing or for some reason my zero changed drastically on its own?


Thank you
Click to expand...

The others have hit on this already. You are off by a full ten inches, and I can't think of a single cartridge that is only a half minute of elevation to 300 yards.

This is only going to happen if you have had a piece of equipment come loose, or a failure somewhere. Even a wildly different body/shooting position isn't going to make up that much of a difference in your zero.

Going back to 100 to verify your zero like you said is a great 'next step'... but I'd be checking my scope base/ring screws before that just in case.
 
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