Question – Zero Distance Adjustment

[rjbFL]

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.

 

[Ozark Marine]

Just fire the weapon at the target. You'll figure it out then.

 

[scooter123]

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.

 

[just plain joe]

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

 

[rjbFL]

Good advice, much thanks

 

[5point5sixGUY]

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.

 

[Lee's Landing Billy]

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.

 

[rockquarry]

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.

 

[cyphertext]

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.

 

[Kadonny]

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.

 

[rockquarry]

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.

 

[cyphertext]

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.

 

[Kadonny]

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?

 

[wayne2356]

still the best video I have seen on the subject

[ame]https://www.youtube.com/watch?v=Klvve0ZG_jo[/ame]

 

[cyphertext]

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.

 

[rockquarry]

Well, maybe I should check my figures. I've certainly been wrong before. I didn't intend to infuriate anyone...

 

[rockquarry]

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.

 

[Kadonny]

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).

 

[5point5sixGUY]

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

 

[rockquarry]

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.