Riddle me this? Ballistic calc vs reality mismatch...

Stammster

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Any optical distortion due to all the wildfire smoke (I.e. similar to a mirage effect)? Maybe the dust particles in the smoke are lubricating the bullet as it travels through the air? Maybe the air is acting more dense - but that should effect drop the opposite of what you are seeing?
 

jebel

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Practical thoughts: it’s a scope issue, as you’ve mentioned, or a difference in set up/hold at 500 that is shifting POI.

Curious thoughts: (along the lines Stammster’s comments) what about the smoke? Are you on the west coast? Is your air quality currently in the “hazardous” category? First, get inside and turn on the air filter. Then think about what all of those additional particles in the air might do. We use air pressure, temp, and humidity as inputs to approximate air density and character, but you have something else effecting the air that the model isn’t accounting for. Seems outlandish, but fun to think about.
 

entoptics

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Any optical distortion due to all the wildfire smoke (I.e. similar to a mirage effect)? Maybe the dust particles in the smoke are lubricating the bullet as it travels through the air? Maybe the air is acting more dense - but that should effect drop the opposite of what you are seeing?
Curious thoughts: (along the lines Stammster’s comments) what about the smoke? Are you on the west coast? Is your air quality currently in the “hazardous” category? ...Seems outlandish, but fun to think about.
Definitely in the "hazardous category". But I'd think all the ash would lead to an increased air density, and therefore a low impact. Fun mental experiments though. :D

I got some more data today, which I will process and post tomorrow. First glance indicates initial results are hopefully a worrisome aberration.

Box test the scope & determine it's ACTUAL inches per hundred yards (IPHY) dialing...
See OP, bulleted point 2), ~ 3/4 of the way down the post...;)

I'm still concerned about the scope though. I have a Vortex PST II I could swap, but I'm running out of time and bullets.
 

Canhunter35

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Scope tracking/parallax error would be my guess
Barrel free floated?
It’s a 1moa gun so hard to accurately measure tracking. Zero it to 500, set dial to what ur calculator says then dial it back to zero for 200 yard shots, u might be an 1” low but so what it’s a hunting rifle
The drift could be spin or rifle cant
 
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Canadian Bushman

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Scope tracking/parallax error would be my guess
Barrel free floated?
It’s a 1moa so hard to accurately measure tracking. Zero it to 500, set dial to what ur calculator says then dial it back to zero for 200 yard shots, u might be an 1” low but so what it’s a hunting rifle
The drift could be spin or rifle cant
This.
Move your error to the short range.

1 moa at 100 is way smaller than 1 moa at 1000

Between mirage, parralax, scope mounting, barrel condition, and weather change your dope will rarely be perfect. Just stick the error where it hurts you the least.
 

dxlbaile

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I'm with JE. This happens to me all the time, even after careful tall target testing, and vertical tracking tests on the scope with calibration in the ballistic app.
I like to use Applied Ballistics custom bullet profiles and therefore cannot change the BC. So, what I do is shoot at 600~700 yards and figure out the drop needed to be spot on. Then I adjust the velocity of the bullet in the app to match those results. After that everything from 700 to 200 yards just falls into place. Out to 1K is good too...
I have to do this all the time too.. I just adjust the velocity to get the group to be where I want.. Usually goood to 1000.
 

BrentM

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I used your data and came up with 6.8 MOA using shooter. Usually with an error that far off at that close of range I'd lean more towards shooter, scope, positional issues.

I would set your phone up and vid yourself shooting. I'd be looking for eye alignment and parallax for potential problems. With the smoke in our air right now it is possible you are seeing an issue but I'd be surprised if that is the case with that large of an error. Also, when zero and shot the 500 groups are in the same position such as prone or at a bench or different positions?
 

25WSM

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I'm thinking your programs and inputs are probably correct. Seems you eluded to shooting again and it was fine. So the problem could have been your rifle set up in your rest. Do you have to move your rest and bags to move from 200 to 500? Do you have a fore end stop on your front rest? Just moving the fore end forwards and backwards in the front rest will change elevation. Maybe front stud hitting bag. I have no issues changing the bc in my program to get the numbers to match up. I've had to do a 50 bump on bc to get things right.
Shep
 

Barrelnut

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This.
Move your error to the short range.

1 moa at 100 is way smaller than 1 moa at 1000

Between mirage, parralax, scope mounting, barrel condition, and weather change your dope will rarely be perfect. Just stick the error where it hurts you the least.
Exactly. This is why I was saying to adjust the app so the dope from the app matches at 700 yards and everything else from 700 in would just fall into place.
 

redleg1013

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Jun 23, 2012
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So your "try dope" isn't lining up with your "true dope".
I would toss the "try dope" but that's just me. The computer can only do so much but the bullet never lies.
 

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