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Posted: 9/19/2002 12:56:44 PM EDT
Eotech 552 on a flattop. Going to use a 50 yd zero. M193. At 25 yds. where should my point of impact be? THANKS!
Link Posted: 9/19/2002 6:27:39 PM EDT
Umm - if you sight a .223 rifle to hit the
bullseye at 50 yards - you won't be able to
hit squat at longer ranges.

However - if you zero the iron sights at a
longer range (say 250yds ) you can still cowitness the eotech - and use it for close
range.

No Way are you going to notice any diff in
point of impact between 25 and 50 yards.
Link Posted: 9/19/2002 7:05:51 PM EDT
Go check this out. This chap seems to be qualified enough:
http://groups.msn.com/TheMarylandAR15ShootersSite/improvedbattlesightzero.msnw
Link Posted: 9/19/2002 7:49:01 PM EDT

Originally Posted By AKsRule:
Umm - if you sight a .223 rifle to hit the
bullseye at 50 yards - you won't be able to
hit squat at longer ranges.



You're new to this whole rifle thing, right?

If you zero the rifle at 50 yards, the bullet will cross the line of sight at 50 yards and again at 200 yards. More importantly, zeroing at 50 yards gives the flattest possible trajectory from 0 to 250 yards.
Link Posted: 9/19/2002 10:04:04 PM EDT

Originally Posted By AKsRule:
Umm - if you sight a .223 rifle to hit the
bullseye at 50 yards - you won't be able to
hit squat at longer ranges.

However - if you zero the iron sights at a
longer range (say 250yds ) you can still cowitness the eotech - and use it for close
range.

No Way are you going to notice any diff in
point of impact between 25 and 50 yards.



You need to stick to Aks because you haven't a clue as to what your talking about with AR15 trajectories.
Link Posted: 9/20/2002 5:09:50 AM EDT
Well guys, should I just sight the thing about dead on at 25, then adjust when I can get out to a 50 yd. range? I believe it should be hitting just a tad low at 25 to be on at 50? I will need to adjust anyway at 50. AKsRule is trying to help, but with an AK focus. If your best case is a 5 MOA AK, "sighting in" is probably just getting on paper ;)
Link Posted: 9/20/2002 5:16:21 AM EDT

Originally Posted By Cleophis:
Well guys, should I just sight the thing about dead on at 25, then adjust when I can get out to a 50 yd. range? I believe it should be hitting just a tad low at 25 to be on at 50



I was looking for it and can't track it down. I think you want the point of impact to be 1" low at 25 yards but I could be mistaken.
Link Posted: 9/20/2002 5:53:18 AM EDT
With irons you want to be 1.2" low at 25 yards. Since the Eotech is a little higher than the irons, you might want to 1.3" or 1.4" low.
Link Posted: 9/20/2002 6:15:39 AM EDT
Many thanks gentlemen. Imposter, your commentary has been temporarily immortalized in my PalmOS memo pad ;)
Link Posted: 9/20/2002 6:17:25 AM EDT
Oh wait, it's on a flattop. Is the eotech on a flattop higher than irons? It appears lower. tks!
Link Posted: 9/20/2002 6:52:52 AM EDT
If you can measure your height over bore, you can use this online ballistics calculator to get the right number.

www.norma.cc/htm_files/javapagee.htm

Ballistic coefficient for M193 is .243 and velocity out of a 20" barrel should be about 3,165 fps.

Ballistic coefficient for M855 is .304 and velocity out of a 20" barrel should be about 3,000 fps.

Any other round you will have to determine velocity and coefficient yourself.

So all you have to do to get the proper zero is plug in your height of sightline and set zero range to 50. Moving the redline on the display will give you specs for any given range.
Link Posted: 9/20/2002 6:56:40 AM EDT

Originally Posted By Cleophis:
Oh wait, it's on a flattop. Is the eotech on a flattop higher than irons? It appears lower. tks!



Get it on paper at 25 yards the 1.2 to 1.3 figures quoted above will do nicely. Then move the target out to 50 yards and you should only be a couple of clicks off at most.

I'll bet the EO Tech on a flattop is pretty close to the 2.6" height over bore of the irons. So the 50yard/200 METER zero (thats about 216 yard for those of you not up on your metric system) should work very well with your setup.
Link Posted: 9/20/2002 7:14:59 AM EDT
Sweet. I'll let ya'll know how it works out. Thanks gentlemen and have a good weekend.
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