Difference between shooting prone position and then from a bench?

RBanta66

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So out shooting today I was shooting prone position. I noticed I had to dial in 2 moa higher than my app said I needed to. I was shooting my 308 with 168 ELDM mv 2745, used Magneto V3. It called for 10.06moa elevation, I had to dial 12moa. I then shot my last group from the bench not changing anything but shooting position and was exactly 2moa high??? Anyone else seen this? I'm still learning!

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Nevada Smith

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Was the parallax properly adjusted in each of the prone and sitting position?

Did you observe a shadow ring around the perimeter of the optic while taking the shot?
 

RBanta66

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I didn't change anything as it was same distance only 30 inches up, I will check next time I get out to the range.

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rfurman24

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I would shoot another day in reverse order but I have seen up to a minute or two change depending on how you shoot prone. I rarely shoot from a bench anymore because of this. Not all setups respond the same.
 

RBanta66

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I actually believe I may of adjusted my parallax. I guarantee I will not do that next time. I will also try what you said Ryan. Thanks for all the great suggestions.. I have shot this distance many times with a different rifle, but it is the first time I've seen this issue.

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Greyfox

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To rule out changes in POI when changing from prone to bench(or other positions), it’s best to shoot same session, load, conditions, scope setting, etc. I like to check this at 200 yards, and use a bipod whether prone or bench. With practice I have found that achieving the same POI is a function of a consistent rifle hold from the various positions. There seems to be a strong tendency for the POI to be roughly .5MOA higher from a bench position when compared to prone. This can often be corrected by proper rifle fit and shooting hold/position.....and, Lots of practice! I have found this easier achieve with heavier rifles(+10 pounds)
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MAD

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So out shooting today I was shooting prone position. I noticed I had to dial in 2 moa higher than my app said I needed to. I was shooting my 308 with 168 ELDM mv 2745, used Magneto V3. It called for 10.06moa elevation, I had to dial 12moa. I then shot my last group from the bench not changing anything but shooting position and was exactly 2moa high??? Anyone else seen this? I'm still learning!

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happens often...that is why I tell clients there is not any benches in the field lol. Once load development has happened and a decent zero.....EVERYTHING is from prone to confirm it. Then I'll add in various positions. This situation is over looked by many but guys that are out there doing "it" know to find the sweet spot between prone and other positions and leave the bench for load testing.
 

Livetohunt

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I only shoot from a bench when the range won’t let me shoot prone or seated off my tripod. I don’t see much of a change on POI though... were you using a bipod in both positions? If your “loading” the bipod differently in each position it could affect it, but I wouldn’t think 2 MOA.
 

RBanta66

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I normally shoot prone and have been for quite some time. I have not noticed the POI shift with my other rifles. I have a Midway shooting mat so I do pre-load my bipod but no more than needed to shoot consistent groups. I did state above that I believe I changed my parallax. This was actually the first time I had taken this rifle out to 500yds with this scope and I'm still getting use to this setup. I did know that a POI shift was possible when changing positions just did not expect that much. I still have plenty of the same ammo loaded so I will double check everything next time I hit the range. Gun shoots pretty darn good for a factory rifle, I was getting just over half MOA at 500yds. Thanks to all for all the great insight into this issue I had, it's very much appreciated!!!

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hereinaz

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I normally shoot prone and have been for quite some time. I have not noticed the POI shift with my other rifles. I have a Midway shooting mat so I do pre-load my bipod but no more than needed to shoot consistent groups. I did state above that I believe I changed my parallax. This was actually the first time I had taken this rifle out to 500yds with this scope and I'm still getting use to this setup. I did know that a POI shift was possible when changing positions just did not expect that much. I still have plenty of the same ammo loaded so I will double check everything next time I hit the range. Gun shoots pretty darn good for a factory rifle, I was getting just over half MOA at 500yds. Thanks to all for all the great insight into this issue I had, it's very much appreciated!!!

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Coming in a little late, but there are many reasons for the possible change.

Mathematically, parallax is not going to make a 2 moa shift. For instance parallax set for 150 yards, if you double that to 300, then if you move your eye so that you can barely see out of it the shadow is so big the view is nothing more than a slit, you will be off by no more than half the distance of your objective. If you have a 50mm objective, then at MOST it will be 25mm. It follows that so if you add another 150 it will be another 25mm. So, if you are looking through a sliver at 500 with absolutely terrible scope shadow, there is no way it is over 10 inches that you are off. If you had parallax even close and if you were fairly centered in the scope, then it is not parallax.

If we eliminate the scope, and what you are seeing, then it is something with the rifle and you or with the environment.

If the mirage were the cause it would be because of time elapsed between shots or because it was drastically different between the ground and the bench, which is a possibility. Mirage really gets bad on the ground here in AZ when the sun heats it up. But, even then 2 moa is a lot.

Another cause, one which I suspect the most is that there is something different between this rifle and your other rifle that causes a positional change between bench and prone. Or, this rifle is a magnum and the others are not. We all know that magnum rifles cause shots to fly high if they are not properly managed. The Hunter's Wedge goes a long ways to solving that problem by providing really solid rear support.

Tell us about this rifle vs. your other rifles you shoot the same from both positions. If there is a difference, maybe it is in the rifle that causes a difference in set up.

 

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