Astigmatism and scopes?

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scottsman

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So I was out at the range zeroing my savage mark ii. I have a vortex crossfire ii 4-12x50 on it. I got it close at 50 meters but wanted the POI to be right on the crosshairs. I get my brother to do it. He is a steadier shot. We get it done. He puts 3 shots through the same hole. I figure we are good to go. I get behind it. I group 3-4 inches above the crosshairs. I don't think it was a flinch because I am capable of a 1 inch group from my own zero. I then rezero'd and put groups on the bullseye.

He has astigmatism. The other times he zero'ed a rifle for me he was wearing contacts and the zero's seemed fine. This time he was wearing glasses. The effect seemed to be amplified at 100 meters. With his zero I would be 8-10 inches high.

Has anyone seen this before? Does astigmatism cause such issues or do I just really consistently twitch the barrel up when I shoot?

Bonus question.
Is an aimpoint better on the handgaurd of a vz 58 or somehow mounted behind the bolt? Always seemed weird to be so far forward on the handguard.
 
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more likely the difference is in how you are holding the firearm. tighter the hold, the lower the group will be on the target. this is especially noticeable with a handgun and slow heavy bullets, you see, the firearm is starting to recoil before the bullet has left the barrel. light hold= higher group, tight hold=lower group. you can test it yourself.
 
I have astigmatism. Even corrected with contacts my friends with normal vision cannot see anything until they completely readjust the ocular.
 
I have an astigmatism with 2 different degrees in each eye. My first red dot scope works for me, I've heard the holographic sight is more of a problem for guys like us. I will try one before I buy.
 
Is this why i see 2 reddots from my bushnell trophy?
One is very clear, the other is slightly offset and very pale.
I was thinking the reddot was defect before checking this thread,
Now i have a doubt that I might be defect.
 
barsik said:
more likely the difference is in how you are holding the firearm. tighter the hold, the lower the group will be on the target. this is especially noticeable with a handgun and slow heavy bullets, you see, the firearm is starting to recoil before the bullet has left the barrel. light hold= higher group, tight hold=lower group. you can test it yourself.
Click to expand...

I would agree with this; when I shoot my two brother's rifles, I'm consistantly 8-10 inches low @ 100. I tend towards a firmer grip from shooting heavier calibres and hard kicking lightweights.
 
barsik said:
more likely the difference is in how you are holding the firearm. tighter the hold, the lower the group will be on the target. this is especially noticeable with a handgun and slow heavy bullets, you see, the firearm is starting to recoil before the bullet has left the barrel. light hold= higher group, tight hold=lower group. you can test it yourself.
Click to expand...

I thought recoil didnt start till the bullet had already left the barrel?
 
MartyK2500 said:
Is this why i see 2 reddots from my bushnell trophy?
One is very clear, the other is slightly offset and very pale.
I was thinking the reddot was defect before checking this thread,
Now i have a doubt that I might be defect.
Click to expand...

Have a friend with normal vision look through it and tell you if it looks okay.
 
scottsman said:
I thought recoil didnt start till the bullet had already left the barrel?
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as soon as the bullet starts to move, there is an opposite force of movement in the other direction. it is the speed/weight of the bullet verses the weight of the gun. all guns have a degree of recoil before the bullet leaves the barrel, with the slower and heavier bullets having the longest "barrel time" which make them more susceptible to shooter error or technique. the design of a revolver or to a lesser degree a pistol with the axis of the bore much higher than the grip makes recoil much more noticeable and sensitive to grip technique. benchrest shooters tend to use heavy rifles which are not as easily disturbed from point of aim as lighter rifles are. the design of some rifles, like my cherished and dust collecting FN FAL have the bore inline with the buttstock for less muzzle flip, although recoil is the same as any other 308.
 
Ar180shooter said:
Have a friend with normal vision look through it and tell you if it looks okay.
Click to expand...

1/3 of the population has an astigmatism. Some with 20/20 vision may still have a mild case. I've read about people who use a red dot sight and the dot looks blurry due to an astigmatism.

To me, my red dot looks a little expanded and blurry with one eye, when I open both eyes, it is normal. I have no explanation for this. I'm sure my eye doctor would know.
 
MartyK2500 said:
Is this why i see 2 reddots from my bushnell trophy?
One is very clear, the other is slightly offset and very pale.
I was thinking the reddot was defect before checking this thread,
Now i have a doubt that I might be defect.
Click to expand...

Many reddots show some sort of "flare", turning it down to the lowest usable level usually helps. Even the more expensive Leupold Delta points can do this. I had two Delta points with the triangular reticle show two superimposed images of the triangle (the bright one, and then a lighter one offset slightly. They went back, Eventually got a decent one.
 
scope zero does change from a person to another
when my hunting Buddy shoots with my rifles, he is almost a mill left
my father will shoot a few clics up and right
this is why you cannot have a rifle adjusted by someone else or use someone else rifle and take the shot at hunting for a long shot

and yes, how the rifle is held will affect the poi a little
just loading the bipod or not at 400 yards + can make a difference between a hit or a miss with a high recoil rifle
 
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