Rifle Zero

[outerlimits]

for years i've zeroed my AR at 200 yds. seemed like a good distance given we shoot stuff from 10 yds to, on occasion 350-400. anyway, was playing with the trajectory tables and noticed something intriguing about longer ranges.

using my loads and rifle, a 200 yd zero gets me about 6" low at 300, 11" low at 350, and about 17" low at 400. using the program and a 50 yd zero shows about 3" low at 300, 8" low at 350 and about 14" low at 400.

so, the question in my mind is why not zero at 50 yds? assuming most of your concern is about hitting long range targets, say 200-400, seems to me the holdover points to be less critical with the 50 yd zero.

thoughts?

[Thordog]

Congrats.

You backed into what most of us are doing already.

T

[lim10gm]

Your original 200yd zero, was probably also ~30 yd zero.

I like a 250yd zero, which also happens to be a 60yd zero with my setup.

[raz-0]

why not? I'm the wrong person to ask, been zeroing my ar at 50yards since I got it.

[stingerjg]

Zero?!? Im supposed to zero my rifle, no wonder i cant hit anything.

Ok.... i Zero my AR for the longest distance im going to need it in a match. If i know there are going to be targets at 100yards, Ill make sure its zero'd for that far. Most matches, I have it zero'd at 50yards and check for holdover/holdunder for 5-50yards. It may be the wrong way to go about it, but its my way.

[kurtm]

50 is ok for a rough zero, but NOTHING will replace zeroing at actuall ranges. There are too many discrepencies in sights to use a "50" for anything othere than getting on paper farther out. KURTM

[outerlimits]

50 is ok for a rough zero, but NOTHING will replace zeroing at actuall ranges. There are too many discrepencies in sights to use a "50" for anything othere than getting on paper farther out. KURTM

kurt-i understand totally why you say that, and subscribe to the same way of thinking, especially considering wind, scope height, etc. all i'm getting at is zeroing at 50 seems to me to be preferred on long range targets, given the trajectory of the bullets-at least in the 300-400 yd range.

i guess another way of saying it is here's a way to reduce the holdover distances. being able to put the point of aim at the top of a plate versus 4-6" above one, at 350 yds seems easier to me.

[wsimpso1]

You guys might check out this site:

http://groups.msn.com/TheMarylandAR15Shoot...esightzero.msnw

It covers a variety of battle sight zero's including being zeroed at 50 yards.

I agree with kurt, there is no substitute for shooting at all distances, knowing what your adjustments and holdovers for different ranges and positions are.

My tactical rifles and competition gun are all dead on at 50 yards and there is a correction card taped to the stock for other ranges... Simple and it works.

The great thing is that if you disagree with me, you can do it some other way. No big deal.

Billski

[AlamoShooter]

I am certain that my long range 69 -75 gr 223 bullets are not yet stable at 50 yards. even at 100 yards , I get a 3/4 group at 100 and thin I get a 1.01" goup at 200. Could be the amount of attention I give to it.

[Overkill]

Outter,

What you're talking about is not actually the "zero". Its what's technically known as the "Initial Point"; its the point where the bullets trajectory first crosses the line of sight, and normall occurs in the 20 to 80 something yard range depending on how far off the barrel the optic/sight line of sight is, how fast the bullet moves, and how far the "real" zero is set for.

You can get a rough approximation of your actual zero by seeing where the gun prints at the IP, but slight measurement errors in the distance to the target, the deviation of the group from the center of the target, variation in bullet velocity, and measurement of the sight height, can all result in big deviations at the zero point.

Review this for more info on external balistics. http://www.steyrscout.org/extbal.htm

This link has a great ballistics calculator that allows you to control every concievable variable and print out balistics charts that cover any distance/interval you choose. http://www.eskimo.com/~jbm/calculations/traj/traj.html

[kellyn]

What Kurt said.

I also like the 250 yard zero with an optic but I may switch over to the 300m zero for iron sights so I can be like Kurt.

[kdmoore]

What Kurt said.

I also like the 250 yard zero with an optic but I may switch over to the 300m zero for iron sights so I can be like Kurt.

Don't laugh ....

I read (and considered) using a zero where there is no cross over (bullet flies parallel to line of sight). So, if your scope is 2.5 inches above bore, site in where your bullet impacts 2.5 inches low at 100 yds.

Idea was you now have a constant holdover from 0 to 100 yds. Such a set up could work at local shoots where our farthest shots are 100 yds.

I considered doing it, but could never make myself even try.

Hmm, wonder what holdovers are like for 150, 200, 300, 400 yards would be like

Ok, now you can laugh.

[Bronco]

Depends on which scope is used as to the zero point. Meopta is zeroed at 200 cause this puts the 300 point of aim at the top of the vetical line below the red dot. Acog zero is at 100 to be correct for the trajectory compensation reticle. Talon was same as the acog so the dot wasn't in the way at 300.

[Dan Sierpina]

Don't laugh ....

I read (and considered) using a zero where there is no cross over (bullet flies parallel to line of sight). So, if your scope is 2.5 inches above bore, site in where your bullet impacts 2.5 inches low at 100 yds.

Idea was you now have a constant holdover from 0 to 100 yds. Such a set up could work at local shoots where our farthest shots are 100 yds.

I considered doing it, but could never make myself even try.

Hmm, wonder what holdovers are like for 150, 200, 300, 400 yards would be like

Ok, now you can laugh.

300 yards was about 17 inches low

[kurtm]

Keith rethink the Meopta. Center of the dot at 250. 400 is the top of the bar. this would place the point of impact at the TOP of the dot at 200, just like a TA-11 doghnut!

And all this time I thought I was using a 300 yard zero with Iron sights because.....Kelly was KURTM

[Bronco]

Kurt, when I start seeing targets out at 400 thats a good plan but as long as 300 plus a little is all you see I want a good hold point for those ranges that are the most common. 100 yd. hold bottom 1/3 of target, 200 dead on center, 250 bottom of dot on top or can just bracket the target between dot and bar 300 bar in lower 1/2 of target, 350 bar in top 1/2 of target. This covers any matches I have ever shot except the Muscleman and the Meopta is not the scope for that match.

Are you back to OKC yet? Hope to catch you at the 3 gun this weekend. KDT

[kurtm]

There you go using logic again Bronco No won't be home untill Feb 14th or so. Have fun! KURT

[MyBoyElroy]

Operative term is "Maximum Effective Point-Blank Zero". Dependent on target size, external ballistics and sight offset. Once determined, zero points can be calculated with precision.

[BPiatt]

My psychiatrist was right... I AM a non-conformist.

My zero range is 180 yards..

I sat down with a ballistics program years ago and kept changing the zero point until I found 180.

With my loads, I hit within 1" of aiming point out to 210 - 220 yards. Then at 300 yards, I hit 8" low, so I just hold on the neck or at the top of the plate.

Bruce

[kurtm]

Bruce has a good method for scopes but it is darn hard to hold the top of a 10" plate at 300yds with Iron sights, or even neck hold a USPSA target. That is why I like the 300Yd zero. It allows me to "see" more of the target at 300yds and for closer shots I can hold twards the bottom of the target and still get good center hits. With a 20" barrel and 3200 fps. 55 gr bullets this puts one 3" high at 100, 4" high at 200 and dead on the post at 300.

For ACOG TA-11 and Meopta Meostar w/ the 2 min dot in the center I use a 250 making it 2" high at 200 and 3" low at 300, but I'm just a conformist...after all the USMC can't be wrong KURT

[benny hill]

I use 250 zero also. Point blank out to there & top of plate at 300 or so.

[ToddS]

With iron I run a 300 yard zero. Headshots @ 100 & 200 get a six o'clock on the neck hold. ( put the head on top of the sight) Dead on at 300. Simple folks got simple ways........

Edited January 23, 2006 by ToddS

[TonyH]

With my Leupold 1.5x5 mark 4 & 50gr. bullets loaded at 3250. I run a 200 yd. zero which is 2" high @ 100, right on @ 50 & 5.5 " low @ 300.

[kellyn]

I now zero at 301 meters with irons and 251 yards with a scope.

[kurtm]

I usually zero a yard or two more than Kelly but probably a yard or two less than Benny KURT