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Old July 22, 2018, 06:20 PM   #1
Ransome
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Whats up with this? -scope noob

Hi, so I have a strange problem happening to me that just does not make sense. I am a scope noob as the title says, so maybe this will make sense to other people who have frequently sighted in and used a scope. The problem is that I get the scope sighted in at 25 yards. Then I move it up to 50 yards, and it hits perfectly on the horizontal axis, but is now about 6 inches above the center. And If I move it out to 100 yards, horizontal is good but the vertical is about a foot above center. You would expect it to go down, not up? I was able to sight in the scope and it is hitting great at 100 yards now. But why is it going up instead of down the farther out I get. This has happened to me on two different scopes. Keep in mind they are 60$ scopes. So is this normal?
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Old July 22, 2018, 07:10 PM   #2
Doyle
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Remember that line-of-sight (i.e. through the scope) is perfectly flat (all in one plane). Bullet path is an arch. The bullet will cross the line-of-sight twice. The first time is relatively close to the muzzle as the bullet travels up in relation to line of site. The 2nd time is the "sight in" point as the bullet is traveling down in relation to line-of-site.
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Old July 22, 2018, 07:25 PM   #3
ice monkey
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Well at least your $60 scopes are tracking well!! There’s another term for you to learn, tracking.” But that’s neither here or there right now. That’s perfectly normal. If you “zero” your scope that close... well here, have a look at this:

http://www.rifleshootermag.com/shoot...llistics_0303/


The first picture should tell the whole story.

Given the rise you’ve stated, I’m guessing your shooting a .243?
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Old July 22, 2018, 07:49 PM   #4
BBarn
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What you describe is basically normal. I believe the result is more pronounced as the vertical distance between barrel bore and scope is increased.
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Old July 22, 2018, 08:21 PM   #5
jmr40
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Your scope is mounted about 1.5" above the centerline of the bore. The bullet leaves the muzzle 1.5" lower than your line of sight. Most people don't realize it, but the muzzle of the rifle is slightly elevated compared to the breach so the bullet leaves traveling in at a very slight upward angle and will travel in an arc. You have the rifle zeroed at 25 yards where the bullet crosses your line of sight going up. At some point it will reach it's apex and begin to fall. When it reaches it's apex, is where you want to zero. 25 yards is way too close.

Most people zero at 100 yards. That means the bullet will be about 3/4" to 1" low at 25 yards and about 1/4" low at 50 yards. At right around 100 yards you'll be at the bullets apex and beyond 100 yards the bullet will be below your line of sight.

Some people zero at 200-400 yards, but that causes your bullets to be several inches high at 100-200 yards. By zeroing at 25 yards you were effectively also zeroing at about 300 yards.
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Old July 22, 2018, 08:59 PM   #6
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Thank you guys, I completely forgot that a bullet travels on an arch. I'm just glad to know that my scopes are fine. I did think it might of had something to do with line of sight, but was not sure. I was shooting .223, but did not exactly measure the vertical axis hits on the target. I more or less guessed 6 inches and 1 foot.
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Old July 23, 2018, 12:35 PM   #7
hagar
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A 25 yard zero is practically the same as a 300 yard zero, at least on an AR15.
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