I currently have my EOTech 552 zeroed at 50 yds.  When shooting upclose (@25 yds.) you aim about 3 inches high to hit your point.  (This shows my ignorance) If zeroed at 25 yds. how would POA differ?

TS

You mean when you shoot point blank with a 25yrd zero?  Or out to 50yrd with a 25yrd. zero.  Sorry just need to make sure I know what you need!

Sorry, that was poorly worded and constructed.  My EOTech currently zeroed at 50yds hits the a 25 yard target about three inches lower than the point of aim. Naturally if I zero the weapon at 25 it will hit the POA at 25.  Where will the bullet hit at 50 yds if zeroed at 25?  And where will it impact in realtion to point of aim at 100?  Thanks,

TS

I used this ballistic calculator [url]http://www.beartoothbullets.com/rescources/calculators/balistics/[/url] to calculate bullet drop/rise using a 55 gr FMJ bullet with a BC of 0.255, muzzle velocity of 3240 fps, and sight height of 2.6".

With a 25-yd zero, you get the following:

00 yds, -2.6"
25 yds, 0"
50 yds, +2.4"
75 yds, +4.5"
100 yds, +6.4"
125 yds, +8.1"
... ...
250 yds, +11.5"
... ...
414 yds, 0"

I just attended a CQB carbine class where we zeroed at 30 yds.  The bullet would be +1.6" at 50 yds, +4.8" at 100 yds, +7.9" at 220 yds, and back to far zero at 364 yds.

The [url=http://groups.msn.com/TheMarylandAR15ShootersSite/zeroingmethods.msnw]improved battlesight zero (IBSZ)[/url] gives a near zero of 50 yds and a far zero of 243 yds, with no more than -2.6" (muzzle) or +2.3" (150 yds) between these ranges.

My question:  Is there a different zeroing method for CQB weapons (100 yds or less)?

Thanks, Gman.  I plan on shooting no farther than 150 yds with this particular weapon.

TS

Then zero at 50 yards.

Even for CQB zero at 50 yards.  If you check the offsets at the closer zeros (say 25y or 30 y) you STILL have to adjust for headshots at 12 yards (or closer) - the difference isn't all that much.  But you don't need it at 25y

By zeroing at 50 yards its COM for body shots, and the holdover for head shots from say 8 yards to 25y is close enough that 1 hold over value  value should work at all CQB distances.  Plus you get that nice flat trajectory +/-2" out to 220y for the longer shots.

Thanks for the real life reasoning and practical necessity for the 50yd zero.

TS

Input Data @ 25 yard zero
Muzzle Velocity: 3240.0 ft/sec
Chronograph Distance: 10.000 feet
Ballistic Coefficient: 0.255  
Drag Function: G1  
Bullet Weight: 55 grains
Sight Height: 2.60 inches
Sight Offset: 0.00 inches
Wind Range Speed: 0 mph
Wind Vertical Speed: 0 mph
Wind Cross Speed: 0 mph
LOS Angle: 0 degrees
Cant Angle: 0 degrees
Target Speed: 0 mph
Target Angle: 90 degrees
Zero Range: 25 yards
Zero Height: 0 inches
Zero Offset: 0 inches
Temperature: 59.6 °F
Barometric Pressure: 29.92 in Hg
Relative Humidity: 0.0 %
Altitude: 0 feet
Air Density: 100 % of Sea Level


Calculated Table
Elevation: 10.354 moa
Azimuth: 0.000 moa

Range Velocity Energy Momentum Drop Windage Lead Time
(yards) (ft/sec) (ft-lbs) (lbs-sec) (inches) (inches) (inches) (sec)
0 3253.7 1292.8 0.79 -2.6 0.0 0.0 0.000
25 3151.8 1213.1 0.77 -0.0 0.0 0.0 0.023
50 3052.2 1137.7 0.75 2.4 0.0 0.0 0.048
75 2954.8 1066.2 0.72 4.5 0.0 0.0 0.073
100 2859.5 998.5 0.70 6.4 0.0 0.0 0.098
125 2766.2 934.5 0.68 8.1 0.0 0.0 0.125
150 2675.0 873.8 0.65 9.4 0.0 0.0 0.153
175 2585.6 816.4 0.63 10.4 0.0 0.0 0.181
200 2498.2 762.1 0.61 11.2 0.0 0.0 0.211
225 2412.6 710.8 0.59 11.5 0.0 0.0 0.241
250 2328.9 662.4 0.57 11.5 0.0 0.0 0.273
275 2247.1 616.6 0.55 11.1 0.0 0.0 0.306
300 2166.5 573.2 0.53 10.3 0.0 0.0 0.340
325 2087.4 532.1 0.51 9.0 0.0 0.0 0.375
350 2010.0 493.4 0.49 7.2 0.0 0.0 0.411
375 1934.3 456.9 0.47 4.9 0.0 0.0 0.450
400 1860.5 422.7 0.45 1.9 0.0 0.0 0.489
425 1788.7 390.7 0.44 -1.6 0.0 0.0 0.530
450 1718.9 360.8 0.42 -5.8 0.0 0.0 0.573
475 1651.2 332.9 0.40 -10.8 0.0 0.0 0.617
500 1585.5 307.0 0.39 -16.5 0.0 0.0 0.664




Input Data @ 50 yard zero
Muzzle Velocity: 3240.0 ft/sec
Chronograph Distance: 10.000 feet
Ballistic Coefficient: 0.255  
Drag Function: G1  
Bullet Weight: 55 grains
Sight Height: 2.60 inches
Sight Offset: 0.00 inches
Wind Range Speed: 0 mph
Wind Vertical Speed: 0 mph
Wind Cross Speed: 0 mph
LOS Angle: 0 degrees
Cant Angle: 0 degrees
Target Speed: 0 mph
Target Angle: 90 degrees
Zero Range: 50 yards
Zero Height: 0 inches
Zero Offset: 0 inches
Temperature: 59.6 °F
Barometric Pressure: 29.92 in Hg
Relative Humidity: 0.0 %
Altitude: 0 feet
Air Density: 100 % of Sea Level


Calculated Table
Elevation: 5.803 moa
Azimuth: 0.000 moa

Range Velocity Energy Momentum Drop Windage Lead Time
(yards) (ft/sec) (ft-lbs) (lbs-sec) (inches) (inches) (inches) (sec)
0 3253.7 1292.8 0.79 -2.6 0.0 0.0 0.000
25 3151.8 1213.1 0.77 -1.2 0.0 0.0 0.023
50 3052.2 1137.7 0.75 -0.0 0.0 0.0 0.048
75 2954.8 1066.2 0.72 1.0 0.0 0.0 0.073
100 2859.5 998.5 0.70 1.7 0.0 0.0 0.098
125 2766.2 934.5 0.68 2.1 0.0 0.0 0.125
150 2675.0 873.8 0.65 2.3 0.0 0.0 0.153
175 2585.6 816.4 0.63 2.1 0.0 0.0 0.181
200 2498.2 762.1 0.61 1.6 0.0 0.0 0.211
225 2412.6 710.8 0.59 0.8 0.0 0.0 0.241
250 2329.0 662.4 0.57 -0.4 0.0 0.0 0.273
275 2247.1 616.6 0.55 -2.0 0.0 0.0 0.306
300 2166.5 573.2 0.53 -4.0 0.0 0.0 0.340
325 2087.4 532.1 0.51 -6.5 0.0 0.0 0.375
350 2010.0 493.4 0.49 -9.5 0.0 0.0 0.411
375 1934.3 456.9 0.47 -13.0 0.0 0.0 0.450
400 1860.5 422.7 0.45 -17.1 0.0 0.0 0.489
425 1788.7 390.7 0.44 -21.8 0.0 0.0 0.530
450 1718.9 360.8 0.42 -27.2 0.0 0.0 0.573
475 1651.2 332.9 0.40 -33.4 0.0 0.0 0.617
500 1585.5 307.0 0.39 -40.3 0.0 0.0 0.664

bvmjethead......you interested in tryin' to balance my checkbook??

NateZ, how are you mounting your EOTech, straight to the flattop?  How far forward?

TS