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Old 01-02-2017, 06:53 PM
rjbFL rjbFL is offline
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Default Question – Zero Distance Adjustment

I have an opportunity to zero at a friends range. Currently, it is set-up for 20 yards.

I want a 50 yards zero, so should I zero 1 inch low at 20 yards?

Thanks in advance.
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Old 01-02-2017, 06:56 PM
Ozark Marine Ozark Marine is offline
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Just fire the weapon at the target. You'll figure it out then.
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Old 01-02-2017, 06:59 PM
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Ozark had it correct. The reason for his statement is that the difference in elevation between 20 and 50 yards won't be more than an inch or so, as a result you will be On Paper with your current sight setup.
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Old 01-02-2017, 07:43 PM
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I currently use a 100 yard zero for my patrol rifle. Other officers use the 50 yard zero. I suggest that you read the following article as the author explains the system better than I ever could. Please try:

Long Gun Zero – Law Officer

After you read the article, if you decide to use either the 50 yard or the 100 yard zero, then use the following link to print out a sight-in target.

100 Yard Zero Target - Documents

This system has worked for me, fellow officers, and operators on our weapons team. I hope that it works for you.

Good luck.

Joe
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Old 01-02-2017, 09:47 PM
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Good advice, much thanks
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Old 01-02-2017, 10:54 PM
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For a 50/200 zero, you want the point of impact to be about an inch low at 25 yards. A 50/200 zero offers the shallowest angle of trajectory. From point blank out to 250 yards the point of impact will be within a few inches (2 or 3) high or low and will be dead on at 50 and 200 yards. No need to adjust for hold overs, just aim for center mass and you'll be good to go.
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Old 01-03-2017, 01:57 PM
Lee's Landing Billy Lee's Landing Billy is offline
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Google...The non-thinking man's trajectory table. It gives all calibers in many weights with in close 0s and the maximum yardage possible for the round to never be over 3 inches high or low.
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Old 01-03-2017, 02:59 PM
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You really limit yourself and the capabilities of your carbine / rifle with a 50-yard zero. For the majority of AR shooters, a 100 yard zero is most practical, regardless of bullet weight. The gun will shoot a little high at 50 yards and a little low at 200.

You'll need to confirm the exact above and below at 50 and 200, but it won't be much. Additionally, if you zero from a good solid padded benchrest and then shoot offhand, prone, or what have you, the zero will likely be affected.

Every shooter is different when it comes to skill, firmness of hold, etc., so it's important to shoot using different positions to see where your gun is shooting, i.e., point of aim vs. bullet's point of impact at various distances.
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Old 01-03-2017, 03:26 PM
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Originally Posted by rockquarry View Post
You really limit yourself and the capabilities of your carbine / rifle with a 50-yard zero. For the majority of AR shooters, a 100 yard zero is most practical, regardless of bullet weight. The gun will shoot a little high at 50 yards and a little low at 200.
Please explain how you "really limit yourself and the capabilities of your carbine / rifle with a 50-yard zero"...

If you look at trajectory charts, with a 50 yd zero, you are never more than 2" high or low all the way out to 250 yards.

With the 100 yd zero, there is no over, you are always going to be low up to and after 100 yards. But by the time you get to 250 yards, you are 6" low!

For defensive use, the 100 yd zero might be better, since at 50 yards out to about 175 yards, you will only be an inch low or less.. so only hold overs, no hold unders to remember. But honestly, either zero will work for self defense distances aimed at center mass.


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Old 01-03-2017, 03:30 PM
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Originally Posted by rockquarry View Post
You really limit yourself and the capabilities of your carbine / rifle with a 50-yard zero. For the majority of AR shooters, a 100 yard zero is most practical, regardless of bullet weight. The gun will shoot a little high at 50 yards and a little low at 200.
Actually, the gun will shoot low at both 50 yards and 200 yards with a 100 yard zero. 100 yards is pretty much the bullet apex on a .223/5.56, so anything up to that and beyond that will hit low. That's why I zero my rifles at 100yds. You only ever think about holdover for targets that are not 100 yards, never holdunder.
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Old 01-03-2017, 04:24 PM
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cyphertext- Simply stated, a 50 yard zero will cause greater bullet drop at 250 yards than a 100 yard zero will. What's stated in my original post is correct.

I suppose if we need to be more exact, specific bullets & weights, ballistic coefficients, and muzzle velocities need to be included, but the basic premise holds true.
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Old 01-03-2017, 04:35 PM
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cyphertext- Simply stated, a 50 yard zero will cause greater bullet drop at 250 yards than a 100 yard zero will. What's stated in my original post is correct.

I suppose if we need to be more exact, specific bullets & weights, ballistic coefficients, and muzzle velocities need to be included, but the basic premise holds true.
What? Not according to any trajectory chart I have seen... look at the one I posted above...

At 250 yards with a 50 yard zero, the impact is about 2 inches low.

At 250 yards with a 100 yard zero, the impact is 6 inches low...

How is a 2 inch drop greater than a 6 inch drop? With a 50 yard zero, I don't even need to attempt a hold over to make that shot.

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Old 01-03-2017, 04:51 PM
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Quote:
Originally Posted by rockquarry View Post
cyphertext- Simply stated, a 50 yard zero will cause greater bullet drop at 250 yards than a 100 yard zero will.
No it won't for a typical .223/5.56 round. See cyphertext's chart. Where are you getting your information from? Can you share your sources?
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Old 01-03-2017, 05:12 PM
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still the best video I have seen on the subject

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Old 01-03-2017, 05:33 PM
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still the best video I have seen on the subject
That video is ok, except for the use of yards and meters interchangeably. At 25 yards and 25 meters, there isn't much difference, but it makes a big difference at 300 meters out.
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Old 01-03-2017, 05:56 PM
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Well, maybe I should check my figures. I've certainly been wrong before. I didn't intend to infuriate anyone...
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Old 01-03-2017, 06:18 PM
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Just checked trajectory on a "Load From A Disk" program. I chose randomly a 55 grain Hornady V-Max, BC of .25 at 2800 fps muzzle velocity. With a 50 yard zero, at 100 yards the bullet is .22" high, and at 250 yards, it is 8.9" low as opposed to 9.4" low with a 100 yard zero. You're right, cyphertext.
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Old 01-03-2017, 06:27 PM
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Well, maybe I should check my figures. I've certainly been wrong before. I didn't intend to infuriate anyone...
No one is infuriated, it's just the way it works. Admittedly it takes a little time to understand it. If the apex of a .223 round is about 100 yards (with a standard sight axis about 3" higher than bore axis) any distance up to 100 yards will hit a target low and anything after 100 yards will hit the target low. If you zero at 50, then the bullet still has 50 more yards that it rises until it starts to fall whereas a 100 yard zero the bullet starts to fall immediately after the 100 yards (approximated of course).
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Old 01-03-2017, 06:31 PM
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Quote:
Originally Posted by rockquarry View Post
Just checked trajectory on a "Load From A Disk" program. I chose randomly a 55 grain Hornady V-Max, BC of .25 at 2800 fps muzzle velocity. With a 50 yard zero, at 100 yards the bullet is .22" high, and at 250 yards, it is 8.9" low as opposed to 9.4" low with a 100 yard zero. You're right, cyphertext.
With a 50 yard zero, at 250 yards the impact will not be 9 inches low, it will be about 3 inches low as I previously stated. I suggest you read from the following...

AR-15 Zeros and Trajectories
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Old 01-03-2017, 08:08 PM
rockquarry rockquarry is online now
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I just checked the "Load From A Disk" trajectory figures with a Hornady load manual trajectory figures; they jive very closely. I'm not expert enough to argue with these sources.
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Old 01-03-2017, 08:29 PM
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I just checked the "Load From A Disk" trajectory figures with a Hornady load manual trajectory figures; they jive very closely. I'm not expert enough to argue with these sources.
You've got something wrong... sight over bore height maybe?
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Old 01-04-2017, 09:14 AM
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I guess I'm just stuck in my Military ways, shoot on a 25m range to zero on a 300m target.

I have yet to shoot at a civilian range, are they normally all set up in yards?
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Old 01-04-2017, 09:24 AM
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I guess I'm just stuck in my Military ways, shoot on a 25m range to zero on a 300m target.

I have yet to shoot at a civilian range, are they normally all set up in yards?
All of them that I have been to are. We don't use the metric system in the civie world.
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Old 01-05-2017, 09:09 AM
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Reid Henrichs just put out a video shooting at multiple distances (100-400 yards) with two rifles with two different zeros (100ydZ & 50/200ydZ) You can see the results for yourself.

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Old 01-05-2017, 09:24 AM
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Reid Henrichs just put out a video shooting at multiple distances (100-400 yards) with two rifles with two different zeros (100ydZ & 50/200ydZ) You can see the results for yourself.

A 100 Yard Zero vs. A 200 Yard Zero - YouTube
Good video that shows what really happens. I like that it even sort of supports my 100 yard zero. Nice.
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Old 01-05-2017, 10:39 AM
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Good video that shows what really happens. I like that it even sort of supports my 100 yard zero. Nice.
There is nothing wrong with the 100 yrd zero, depending on what your intended ranges and type of shooting you want to do.

For defensive shooting, it may be better than the 50 yd zero simply because there are no hold overs... either low or on. And aim for center mass and it isn't much difference.
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Old 01-05-2017, 12:54 PM
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My chronograph says that my rifle shoots AE M855 at an average muzzle velocity of 2928fps out a 16in barrel.

50yd zero with 2.5in sight over bore keeps the bullet path within about an inch and a half of line of sight out to 230yds then about three inches below line of sight at 250yds.

100yd zero keeps the bullet path within about an inch and a half of line of sight out to 180yds then about six inches below line of sight at 250yds.

I live in the woods of Tennessee where shooting other than at the range isn't likely to be further than 250yds unless firing down the highway . I shoot offhand and use a 1x red dot for point and click center mass shooting.

So..... while some may quibble that a 100yd zero has a flatter bullet path at intermediate distances or that it's further below line of sight from intermediate distances to 250yds than a 50yd zero, either would serve my expectations of the rifle, ammo, sighting system, terrain and my abilities for the intended use of the rifle. That said, I use a 50yd zero.

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Old 01-05-2017, 01:03 PM
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So..... while some may quibble that a 100yd zero has a flatter bullet path at intermediate distances or that it's further below line of sight from intermediate distances to 250yds than a 50yd zero, either would serve my expectations of the rifle, ammo, sighting system, terrain and my abilities for the intended use of the rifle. That said, I use a 50yd zero.
I use the 50 yard zero because I can actually see the target to sight in at 50 yards!
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Old 01-05-2017, 01:39 PM
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There is nothing wrong with the 100 yrd zero, depending on what your intended ranges and type of shooting you want to do.

For defensive shooting, it may be better than the 50 yd zero simply because there are no hold overs... either low or on. And aim for center mass and it isn't much difference.
I assume you meant there are no hold unders with the 100yd zero. You either aim at center mass or aim high. That's why I like it, simplistic.
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Old 01-05-2017, 02:09 PM
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I assume you meant there are no hold unders with the 100yd zero. You either aim at center mass or aim high. That's why I like it, simplistic.
Yep... brain and fingers didn't play well together.
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Old 01-05-2017, 04:12 PM
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Yep... brain and fingers didn't play well together.
Been there, done that. I knew what you meant though
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Old 01-06-2017, 09:00 AM
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I use the 50 yard zero because I can actually see the target to sight in at 50 yards!
Yup... those practical realities have a way of creeping into the equation.

Kinda like me agonizing over holdover with a calculator. Shooting offhand with a 1x red dot at the distances we're talking about, holdover is more of a discussion exercise than practical reality for me. Point-click-ding. I mean... that steel plate at 100yds will never know that my aim might have been an inch off, nor will the plate at 200yds know that I was aiming one tenth of an inch too high. And the plate at 50yds doesn't even give me a special ding for being zero. We don't have a 250yd plate at the club, but the idea that while shooting offhand with a 1x red dot I'm going to adjust my hold two inches.... uh.... that's eyesight skill level bragging rights I simply don't possess.

Now of course a steel plate ain't the same as a bad guy. Still, I doubt I'll hear any center mass complaining from a bad guy.
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Old 01-06-2017, 03:34 PM
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The only targets I worry about are hogs and deer and knowing where your rifle shoots is what I count on. That means I shoot unknown distances as often as I can so that I can hit what I want when I need to. 200 yards is a pretty good stretch for anything I have ever hunted except antelope,got one of those at 400 ,once!
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