ar 15 sights


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akashooter
November 8, 2006, 10:38 AM
ive shot ar 15 with scopes but not with the regular rear apature, and front sight. with good eyes how far can you see? how far until the bullets start dropping and you have to adjust the elevation?

thanks for all your help !

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RNB65
November 8, 2006, 11:07 AM
Depends on your eyesight and the type of ammo you're using. At Camp Perry they shoot 600yds with iron sights. Also, bullets never fly on a straight line. The second it leaves the muzzle it begins to drop. How much compensation you have to give it depends on the velocity of the bullet and the distance you use to zero your sights.

30Cal
November 8, 2006, 11:09 AM
Out to 300yds, the rifle shoots pretty flat (within say 5" of the point of aim). After that, you'd have to hold-over or come up on the elevation.

Ty

Lebben-B
November 9, 2006, 07:25 AM
Also, bullets never fly on a straight line. The second it leaves the muzzle it begins to drop.

Not to nit pick, but bullets from rifles fire flat for a short distance, then rise. As the round sheds velocity, gravity take it's toll and the round begins to fall. For example, an AR/M16 with a 20" barrel firing M855 Ball (62 gr FMJ) at a 300m target, the round fires flat for about 35m and then begins to rise. At ~200m the round reaches the height of it's arc. It has also lost enough of it's velocity for gravity to exert it's influence on the round and the round begins to descend, crossing the muzzle line (an imaginary line drawn from the muzzle to the target) at around 300m.

Mike

Blackfork
November 9, 2006, 07:43 AM
Bullets start dropping the moment they leave the barrel. They do not rise above a line parallell with the bore. Bullets SEEM to arc because every barrel and sight set are set up so that the bore points slightly up.

Notice- to move an AR/M16 zero from 100 yards to 600 yards, you add about 30 1/2 MOA clicks of elevation on the rear sight. As the rear sight is elevated, with the eye looking through the peep at the 600 yard target, the rear of the barrel is depressed...raising the muzzle and pointing the barrel higher to arc the bullet out further.

I repeat: this is commonly held misinformation. Bullets do NOT rise.

A level barrel fired over level ground would NEVER see the bullet rise above the line of the bore.

Gravity: It's not just a good idea, It's the LAW.

Dave P
November 9, 2006, 07:51 AM
"Not to nit pick, but bullets from rifles fire flat for a short distance, then rise."

What causes them to rise - Is this due to the so-called Coriolis force?? :banghead:

Dr. Dickie
November 9, 2006, 08:17 AM
I think this misconception comes about because most often (IMO) when someone is explaining ballistics, they use the example of the muzzle pointed slightly elevated from flat (therefore, you see the bullet rise slightly, then drop into the target). This is true for long shots (where elevation above 90 degrees is needed) and too a much, much smaller degree for close shots; however, gravity does not take a holiday. It begins to work on the bullet the moment it is no longer supported by the barrel (actually it is even working on the bullet in the barrel, but the barrel puts an equal but opposite force on the bullet--resulting in a additional frictional force; albeit insignificant).
Any physics folks can correct anything I got wrong (it has been quite a while since I did the math).
So in reality, for most shots the bullet does rise slightly before dropping, but this is because of the angle of the barrel not a suspension of gravity.

ny32182
November 9, 2006, 09:30 AM
The bullet travels in a parabolic arc based on the angle of the barrel when the bullet leaves the muzzle. It does not "rise" on its own. Its vertical velocity component is dictated by an upward force imparted by the barrel angle, and a downward force due to gravity. Thats it.

A bullet that is fired perfectly horizonally to the ground, and a bullet that is dropped from the same height as the muzzle will hit the ground at the same time, and neither will ever rise above the level of the muzzle. Vertical and horizontal velocity components operate independent of each other.

RNB65
November 9, 2006, 10:10 AM
Not to nit pick, but bullets from rifles fire flat for a short distance, then rise.

That is incorrect. The bullet never rises above the axis of the bore. The bullet may rise above the line of sight, but that's because the axis of the bore is above the line of sight. The bullet begins dropping (relative to the bore axis) the micro-instant it leaves the muzzle and continues to drop until it hits something.

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