How accurate must the zero range be?

AR10ShooterinNC

AR10ShooterinNC

Happy to be here
Supporting Member
Joined
Dec 23, 2016
Messages
13,661
Location
High Point
Rating - 100%
9   0   0
How accurate must the 100 yard zero be to make hits out to 1000 yards? Is it plus or minus 1 yard, 1 foot, 6 inches? Where to I measure from? I have read from the end of the barrel and other have said from the turrets of the scope.
 
AR10ShooterinNC said:
How accurate must the 100 yard zero be to make hits out to 1000 yards? Is it plus or minus 1 yard, 1 foot, 6 inches? Where to I measure from? I have read from the end of the barrel and other have said from the turrets of the scope.
Click to expand...

Ideally you want to be as close as you can be but if you're within say 5 yards plus/minus, you should be fine.
 
As long as you are consistent, it really doesn’t matter. Always use the same form of measurement for all measurements.
 
Run one of the ballistics apps and play with the numbers to get a better feel of what's going on.

What kind of target are you looking to hit at 1000yds, a 10" plate, a refrigerator?
 
Last edited:
A perfect no wind zero at 100 is ideal. You need to know your ammo specs bullet weight and velocity to give you your come ups at 1000. JBM is great for that.

Once you find out your come up for 1000, you need to see how much elevation you have available on your scope. Depending on bullet weight and velocity you will need 32"-36" of elevation at 1000, or you are going to have to play with hold overs.

Theoretically, if you can hold 1" at 100 you can hold 10" at 1000. Normally at Butner we could put a new shooter on target on a fairly calm day in 3-6 shots.
 
REELDOC said:
A perfect no wind zero at 100 is ideal. You need to know your ammo specs bullet weight and velocity to give you your come ups at 1000. JBM is great for that.

Once you find out your come up for 1000, you need to see how much elevation you have available on your scope. Depending on bullet weight and velocity you will need 32"-36" of elevation at 1000, or you are going to have to play with hold overs.

Theoretically, if you can hold 1" at 100 you can hold 10" at 1000. Normally at Butner we could put a new shooter on target on a fairly calm day in 3-6 shots.
Click to expand...
I'm using a 223 AR-15 , 20" barrel with 69 gr and 77 gr SMK, looking to hit an IPSIC torso plate 600 to 1000 yards. I have my muzzle velocity (69 gr at 2925fps, 77 gr at 2810), using a chrono. I'm just wondering if I input 100 yards as the zero, but it is really 95 yards, how much will that change the data?
 
If you have 95 yards, no problem. You can use the following as basic come-ups for your bullets. 223's have problems at 1000, but I've done it using hold overs.

Trajectory
Input Data
Manufacturer:SierraDescription:MatchKing
Caliber:0.224 inWeight:69.0 gr
Ballistic Coefficient:0.169 G7 (ICAO)
Muzzle Velocity:2925.0 ft/sDistance to Chronograph:10.0 ft
Sight Height:1.50 inSight Offset:0.00 in
Zero Height:0.00 inZero Offset:0.00 in
Windage:0.000 MOAElevation:0.000 MOA
Line Of Sight Angle:0.0 degCant Angle:0.0 deg
Wind Speed:10.0 mphWind Angle:90.0 deg
Target Speed:10.0 mphTarget Angle:90.0 deg
Target Height:12.0 in
Temperature:59.0 °FPressure:29.92 in Hg
Humidity:0 %Altitude:0.0 ft
Vital Zone Radius:5.0 in
Std. Atmosphere at Altitude:NoPressure is Corrected:Yes
Zero at Max. Point Blank Range:NoTarget Relative Drops:Yes
Mark Sound Barrier Crossing:NoInclude Extra Rows:No
Column 1 Units:1.00 inColumn 2 Units:1.00 MOA
Round Output to Whole Numbers:No
Output Data
Elevation:3.458 MOAWindage:0.000 MOA
Atmospheric Density:0.07647 lb/ft³Speed of Sound:1116.4 ft/s
Maximum PBR:338 ydMaximum PBR Zero:288 yd
Range of Maximum Height:161 ydEnergy at Maximum PBR:645.6 ft•lbs
Sectional Density:0.196 lb/in²
(yd)(in)(MOA)(in)(MOA)(ft/s)(none)(ft•lbs)(s)(in)(MOA)
RangeDropDropWindageWindageVelocityMachEnergyTimeLeadLead
Calculated Table
0-1.5***0.0***2934.52.6281319.10.0000.0***
100-0.0-0.00.90.92655.82.3791080.40.10718.918.1
200-3.5-1.73.91.92391.62.142876.20.22739.919.0
300-13.1-4.29.22.92143.21.920703.60.35963.220.1
400-30.3-7.217.34.11910.21.711559.00.50789.321.3
500-57.1-10.928.75.51690.21.514437.60.674118.722.7
600-96.1-15.344.17.01481.91.327336.40.864152.024.2
700-151.1-20.664.38.81286.31.152253.51.081190.326.0
800-227.2-27.190.610.81110.20.994188.81.333234.528.0
900-331.3-35.2122.513.01022.60.916160.21.616284.430.2
1000-468.6-44.7157.615.0969.80.869144.11.918337.532.2

Trajectory
Input Data
Manufacturer:SierraDescription:HPBT MatchKing™
Caliber:0.224 inWeight:77.0 gr
Ballistic Coefficients:0.343 [0-1800], 0.362 [1800-2500], 0.362 [2500-5000] G1 (ASM)
Muzzle Velocity:2925.0 ft/sDistance to Chronograph:10.0 ft
Sight Height:1.50 inSight Offset:0.00 in
Zero Height:0.00 inZero Offset:0.00 in
Windage:0.000 MOAElevation:0.000 MOA
Line Of Sight Angle:0.0 degCant Angle:0.0 deg
Wind Speed:10.0 mphWind Angle:90.0 deg
Target Speed:10.0 mphTarget Angle:90.0 deg
Target Height:12.0 in
Temperature:59.0 °FPressure:29.92 in Hg
Humidity:0 %Altitude:0.0 ft
Vital Zone Radius:5.0 in
Std. Atmosphere at Altitude:NoPressure is Corrected:Yes
Zero at Max. Point Blank Range:NoTarget Relative Drops:Yes
Mark Sound Barrier Crossing:NoInclude Extra Rows:No
Column 1 Units:1.00 inColumn 2 Units:1.00 MOA
Round Output to Whole Numbers:No
Output Data
Elevation:3.453 MOAWindage:0.000 MOA
Atmospheric Density:0.07647 lb/ft³Speed of Sound:1116.4 ft/s
Maximum PBR:340 ydMaximum PBR Zero:290 yd
Range of Maximum Height:162 ydEnergy at Maximum PBR:746.8 ft•lbs
Sectional Density:0.219 lb/in²
(yd)(in)(MOA)(in)(MOA)(ft/s)(none)(ft•lbs)(s)(in)(MOA)
RangeDropDropWindageWindageVelocityMachEnergyTimeLeadLead
Calculated Table
0-1.5***0.0***2934.12.6281471.70.0000.0***
100-0.0-0.00.90.82668.52.3901217.30.10718.918.0
200-3.5-1.73.71.82418.02.166999.40.22539.718.9
300-12.9-4.18.72.82181.21.954813.30.35662.719.9
400-29.6-7.116.23.91958.01.754655.30.50188.221.1
500-55.5-10.626.85.11746.81.565521.60.663116.722.3
600-92.8-14.840.96.51545.81.385408.50.846148.923.7
700-144.7-19.759.38.11368.31.226320.11.052185.225.3
800-215.2-25.782.29.81219.91.093254.41.285226.227.0
900-309.2-32.8109.811.61106.30.991209.21.544271.728.8
1000-431.5-41.2141.513.51025.00.918179.61.826321.430.7
 
If you use an app like Strelok you can enter all your data and play with a 95yd zero or 100yd zero and set your adjustments accordingly.
 
  • Like
Reactions: Tim
You’ll need to true your data at 600 for mv and then true the bc at 1000. The zero difference won’t matter much after truing.


Sent from my iPhone using Tapatalk
 
AR10ShooterinNC said:
What happens if I tell the app my zero is 100 yards, but in realty it is only 95 yards?
Click to expand...
Why would you lie to your app?


Plug in either value and see the difference at range. You can tell it your zero is at 83.4yds and it will caluclate your trajectory to whatever range you want. Then you will have an idea of how much difference it makes. That's the beauty of it. I do it often to see which zero I prefer 100, 200 or 300, for example. Then I look at the drops along the way and pick which trajectory I prefer.

Even if it doesn't match your gun exactly, due to other factors, it gives you a trend.
 
Last edited:
frakncylons said:
Im kinda trying to follow along. What do you mean by “true data” and “true bc”? Thx.
Click to expand...
“Truing” your data is essentially confirming at each distance, then changing your inputs until your calculator
matches reality.

Get your hundred yard zero, run the numbers to get your 600yd drop. Then go shoot 600. Tweak your muzzle velocity entry until the calculator recommended adjustment matches your actual confirmed adjustment. Usually no more than a couple clicks either way.

Rule of thumb is to tweak your muzzle velocity entry out to 600 and then “true” again at 1,000 by tweaking the ballistic coefficient entry.

Most apps/calcators have specific “truing” fields and processes.
 
Last edited:
@AR10ShooterinNC , nobody seems to have proposed an answer to your actual question....

Measure the zero from muzzle to target. But, for practical purposes, the ~16-24” from chamber to muzzle won’t matter much.
 
Last edited:
Tim said:
@AR10ShooterinNC , nobody seems to have actually proposed an answer to your actual question....

Measure the zero from muzzle to target. But, for practical purposes, the ~16-24” from chamber to muzzle won’t matter much.
Click to expand...
Trying to teach a man to fish...

Reeldoc's tables may have been overwhelming. So, here's some simple calculated data based on your information...

77gr SMK with a muzzle velocity of 2810 and a 100yd zero is down 438.90 inches at 1000yds. With a 95yd zero it's down 439.09 inches.
For the 69gr SMK with a muzzle velocity of 2925 the 100yd zero is down 514.25 inches at 1000yds and the 95yd zero is down 514.41 inches.


Your mileage may vary.
 
When you true the data to targets, especially longer out, your software will adjust as needed.

ie.
@900 yards, data says X mils... but it's actually X.2... when you put it into your ballistic software, it should compensate the entire DOPE chart for you
 
Scope/Muzzle isn't enough to make a real difference and the ballistic software available is good, but sometimes it's not exact, but a very good reference point to get you close, and then you will fine tune your setup from there.

When you are out there, take some notes for your specific setup.
 
You must log in or register to reply here.
Back
Top Bottom