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Posted: 1/11/2005 5:05:27 AM EDT

I'm shooting an AR10 with an A2 FSB and a detachable carry handle and am having problems zeroing.  Impact is way too high.  I have installed the Bushmaster taller front site post and managed to get it down to only 5" high at 50 yards.  If I raise the front post any farther it will be above the wings on the FSB.  

What I would like to know is if anyone can tell me how far down range the projectile will be when it crosses my site line.  I don't have access to a ballistics calculator.

Thanks for the time and help.

147 grain FMJ
2750 fps
20" barrel
site line 2.5" above bore line
5" high at 50 yards

Let me know if I have missed any data.
Link Posted: 1/11/2005 6:09:56 AM EDT
I'll assume standard atmospheric conditions at 1400' ASL...  Assuming .398 for the BC (closest I could find to a 147gr mil round was a 150gr FMJ-BT).

50 +5
100 +11.2
150 +16.1
200 +19.5
250 +21.3
300 +21.4
350 +19.5
400 +15.5
450 +9.1
500 +0.2

You effectively have a 500y zero.
Link Posted: 1/11/2005 6:23:31 AM EDT


Thank you.  That is just what I needed.  Now to decide whether to remove it and install a gas block with detachable front site or leave it the way it is.

I'm not sure a 500 yard zero will do me any good.
Link Posted: 1/11/2005 6:24:58 AM EDT
A.K.A. the famous 16 yard zero:

Here's the track:

Link Posted: 1/11/2005 6:27:36 AM EDT


Very impressive.

Link Posted: 1/11/2005 6:27:49 AM EDT
Disregard 2nd image above - wrong BC.

Try this one:

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