5.56 Bullet Drop at CLOSE range


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mp510
October 27, 2008, 01:03 PM
Ideally, my plan is to check before I ever do apply it, but I want to get some idea of what sort of drop to expect at 10, 15 and 30 feet.

I'm using a carry handle rear sight on a 20" A4. 55 grain ball ammo. My rifle is zeroed at 50 yards.

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rcmodel
October 27, 2008, 01:06 PM
In practical terms, there is no "drop" at those ranges.

What you do have is a carry handle sight mounted some 2 1/2" above the bore line.

SO, again for all practical purposes, the bullet will strike 2 1/2" below where you are aiming at very close range.

rcmodel

Tarvis
October 27, 2008, 01:08 PM
You mean how much should you expect the bullet to rise, right? Unless you are a math major and are looking for a negative rise. Check this ballistic calculator (http://www.eskimo.com/~jbm/calculations/traj/traj.html) for some comparable values.

Basically, at the muzzle you will be 2 1/2" low, and at 50 yards be at 0". Depending on the muzzle velocity of the cartridge and the ballistic coefficient, the bullet will most likely rise a little bit then begin to fall below the point of aim. Play around with that calculator and see what kind of values you can get.

lions
October 27, 2008, 01:09 PM
rcmodel got it.

Just go shoot it at those ranges anyway so you feel comfortable with it.

hags
October 27, 2008, 01:11 PM
In practical terms, there is no "drop" at those ranges.

What you do have is a carry handle sight mounted some 2 1/2" above the bore line.

SO, again for all practical purposes, the bullet will strike 2 1/2" below where you are aiming at very close range.

rcmodel

Yep, I have one of my ARs with an Eotech sighted at 25 yards. It is dead on at from about 15 yards out ot 25 yards. Any less than 15 yards and you have to factor in the difference between the bore and line of sight from your sights.

mp510
October 27, 2008, 01:35 PM
I understand- thanks.

gotime242
October 27, 2008, 01:39 PM
I went out one day with my 50 yard sighted red-dot and recorded where the bullet hit was in my red-dot's "T" at 7-10yrs, 20-25yrds and so on. That was if im in an environment of oh say...10 yards (in a house) i could take a shot and know exactly where its going.

HorseSoldier
October 27, 2008, 03:35 PM
Yep, I have one of my ARs with an Eotech sighted at 25 yards. It is dead on at from about 15 yards out ot 25 yards. Any less than 15 yards and you have to factor in the difference between the bore and line of sight from your sights.

The six o'clock position on the EOTech outer reticle is a pretty workable hold over for really close in work.

publiuss
October 27, 2008, 10:00 PM
RCmodel got it, bullets do not rise, they only drop. Impact depends on distance you have sighted your gun in for, and the impact distance. "Your" impact distance dictates you will be shooting higher than your sight picture b/c that is where the rifle is pointing.

possum
October 27, 2008, 10:31 PM
Any less than 15 yards and you have to factor in the difference between the bore and line of sight from your sights.
yep this is called offset, approx 2.76"

anyone need a visual aid?
this is a target that was shot at 7yds, with my ar and eotech, i aimed at the top of the dark colored man's head to hit him where the rounds landed.
http://i9.photobucket.com/albums/a98/rollins_joshua/arhostagework.jpg

taliv
October 27, 2008, 10:47 PM
i usually aim about where the staple is (elevation-wise) between 3-7 yrds


bullets do rise, however.

janobles14
October 27, 2008, 10:48 PM
think of it this way.

if you are at 50 yds or nearer and want to shoot someone between the eyes, aim at their hairline.

gotime242
October 28, 2008, 10:08 AM
Here is another visual aid,

look at the BOTTOM MIDDLE white plate.

I was aiming at the center, at 7 yards. The two shots below is where it hit.

http://i38.tinypic.com/2a6k1vl.jpg

Dr. Tad Hussein Winslow
October 28, 2008, 10:11 AM
It doesn't drop; it rises at short range. You want to aim about 2" HIGH under 20 yards, and about 1" HIGH at 30 yards, because the bullet path is under the line of sight, rising up. After that, aim dead on and it's "close enough".

gotime242
October 28, 2008, 10:52 AM
http://i38.tinypic.com/1z227pg.jpg

rem2429
October 28, 2008, 03:51 PM
It doesn't RISE, the bullet begins to drop the instant it leaves the barrel. The line of sight starts above the bore axis at x height and drops below it intersecting with the trajectory of the bullet at the zero range...and another range as well. See chart above.
Imagine the silouette targets above displaced vertically rather than horizontally...One could easily shoot the lower guy (hostage) if one was aiming at the bad guys head.

I love the eotech for rifles because as described above, the inferior border of the eotech is just about right at 25 yards and under with a 50 yard zero on an AR.

taliv
October 28, 2008, 04:02 PM
you need to recalibrate your perspective. the line of sight doesn't drop :) it is horizontal, perpendicular to gravity. although the barrel is no longer counteracting the pull of gravity once it leaves the barrel, the bullet gets further away from the Earth (i.e. rises) for almost 150 yrds, before it starts getting closer to the Earth (dropping)

Owen
October 28, 2008, 04:16 PM
rem2429, I understand where you are coming from, but you aren't quite right.

If line of sight is horizontal (0 degrees elevation) then the centerline of the bore is angled up. The initial velocity of the projectile has a positive vertical component, i.e., the bullet is closing with the line of sight, which is ABOVE the bore line. The bullet rises into the line of sight.

If you had a rifle on a perfectly flat plain, with sheets of paper every 10 feet out to the zero distance of 50 meters, and measured the distance from the ground to the holes in the paper, the holes would be farther and farther from the ground as you approaced 50 yards.

The fact that the bullet is moving closer to the line of sight, which is above the line of bore would jive with just about anyone's definition of the bullet rising.

Now if the bore were horizontal, so the line of sight angled down, then you would be right. The bullet never rises above the Line of the Bore.

However, as shooters, we rarely, if ever, know where the line of the bore is, only the line of sight. For this reason, as shooters, the line of sight is the best frame of reference.

With the Line of sight as the reference frame, the bullet most definitely rises.

raz-0
October 28, 2008, 04:27 PM
It's not the bullet rise, it's sight offset.


for an AR with carry handle sights, call it about 5" up close, and stop worrying much about it at 25 yards.

At least with a 16" barrel sighted with a 50 yard zero.

Cles up, there's about 4-5" of sight offset, so hits are about 4-5" low vs. point of aim. at about 15 yards, it's about an inch low. At 50yards it's zeroed. At 100 it is about an inch high. At 200 it is zeroed. At 350, it's about 9-10" low or therabouts. Very usable setup.

mp510
October 28, 2008, 05:37 PM
It's not the bullet rise, it's sight offset.
Thanks. My wording was off. I probably should not have implied cartridge trajectory as i did. I knew I had read an article about having to hold slightly over at 'room distance' and I wanted to get a little bit more info on that.

SaMx
October 28, 2008, 05:43 PM
the bullet rises only because it's shot at a slight upward angle (assuming the sights are perfectly level, and the rifle is zeroed at a farther distance). It starts to accelerate downwards immediately due to gravity however.

gotime242
October 28, 2008, 05:48 PM
"The .223 is being pulled down by gravity from the second its being shot out of a slightly pointed up barrel."

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