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Paralax?
Snigley
Member Posts: 134 ✭✭
This may be a simple question to some of you more knowledgeable guys, but I suck at physics and need an explanation. I recently purchased a flat top upper for my AR because I didn't like having the scope on the carry handle 7 inches above the barrel. I installed the scope on the new upper and fired a couple shots at 25 yards to make sure I was on paper. I was only an inch or so low so I corrected the point of impact and moved the target out to 50 yards. At 50 yards I was grouping about 5 inches high. I lowered it and moved it to 75 yards. Now it's three inches high. Another correction and moved it to 100 only to be 2 inches high. Another adjustment put it steadily in the center. I ran out of ammo and didn't get to see what happens if I move it back to 50 yards. It groups great at a set distance Any ideas what's going on?
Comments
https://www.hornady.com/team-hornady/ballistic-calculators/ballistic-resources/external-ballistics
Height above the bore, initial velocity and the ballistic coefficient of the bullet are factors in your trajectory.
Spend some time playing with a ballistic program to see what each factor does to the trajectory.
https://www.hornady.com/team-hornady/ballistic-calculators/#!/
The scenario described does not involve "parallax", it's simply the rise of the bullet from bore line to scope axis.
Yes, I had to sight my AR to 1-1/2" low at 25 yards to be 2" high at 100 yards.
Let's clarify something first. The bullet does not rise after it leaves the muzzle if the barrel is perfectly horizontal. There is some REAL good information in this link. http://www.rifleshootermag.com/shooting-tips/shooting_tips_ballistics_0303/
Michael
Model 1892 / 61 Collector, Research, Valuation
Hello,
Let's clarify something first. The bullet does not rise after it leaves the muzzle if the barrel is perfectly horizontal. There is some REAL good information in this link. http://www.rifleshootermag.com/shooting-tips/shooting_tips_ballistics_0303/
Michael
Not sure if you knew this but nobody fires a rifle with the barrel perfectly horizontal. So in practical terms the bullet is rising to the scope axis.