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Page AK-47 » AK Discussions
AK Sponsor: palmetto
Posted: 4/15/2003 10:21:26 AM EDT
Just installed a MOJO rear aperture sight on my SAR-1, definitely an improvement over the standard AK rear sight.

I know how to zero the original rear sight at 25 meters, and I know the 7.62 x 39 mm isn't a flat-shooting round.

But is there any way I can shoot where POI = POA and have the trajectory within + or - 4", from the muzzle out to a reasonable range for this cartridge, say 200 yards?

This would be similar to the "Improved Battlesight Zero" for the AR-15/M-16.

Unfortunately, I don't have access to a ballistic calculator, which would have made this a lot easier to figure out.

Thanks,
Gabe
Link Posted: 4/15/2003 2:47:50 PM EDT
[#1]
Link Posted: 4/15/2003 3:06:41 PM EDT
[#2]
Hey Ken, how about a chart for an AK in .223?
Link Posted: 4/15/2003 3:28:47 PM EDT
[#3]
Link Posted: 4/15/2003 8:29:33 PM EDT
[#4]
Ken, thanks for the excellent information.

I found an online ballistics calculator at Beartooth Bullets:

www.beartoothbullets.com/rescources/calculators/balistics/

I plugged in information from Head's Bunker about Kobra collimator sight zeroing (ballistic coefficient):

headsbunker.nothingbutguns.com/html/article_trajectory.html

And information on the Federal (American Eagle) 124 gr. FMJ 7.62 x 39mm round:

www.federalcartridge.com/ammocat20.asp?s1=1

I measured the height from the center of the SAR-1 bore to the top of the front sight post, which was 2".

Crunching the numbers revealed the following:

Range   Velocity   Energy   Momentum    Drop
(yards) (ft/sec)  (ft-lbs)  (lbs-sec)  (inches)

 0     2300.0     1444.7     1.26      -2.0

 25    2232.0     1360.5     1.22      -0.0

 50    2164.7     1279.7     1.18       1.6
 75    2098.5     1202.6     1.15       2.7
 100   2033.4     1129.2     1.11       3.3
 120   1982.2     1073.1     1.08       3.4
 125   1969.5     1059.4     1.08       3.3
 150   1907.0      993.1     1.04       2.9
 175   1845.7      930.4     1.01       1.8

 200   1785.9      871.0     0.98       0.1

 225   1727.4      815.0     0.94      -2.3

 235   1704.5      793.4     0.93      -3.5

 250   1670.5      762.1     0.91      -5.5
 275   1614.9      712.3     0.88      -9.4
 300   1560.9      665.4     0.85     -14.1

The way I interpret this is:

1) If you zero at 25 yards, you'll have a "far zero" of 200 yards;

2) The bullet will be no higher than 3.4" or lower than -3.5" anywhere from the muzzle to 235 yards.

3) I think this would be a decent battlesight zero, given the typical use of the AK-47 - "we ain't talkin' 'bout snipin' heah."

This 25-yard range has the advantage of being available at almost any shooting facility, even indoors.

Please feel free to point out if I am completely (or even partially) full of s**t, or if I am just reinventing the wheel.
Page AK-47 » AK Discussions
AK Sponsor: palmetto
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