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13grandy
07-01-10, 20:04
Anyone know what the effective zero of a 5.56 55gr M193 round would be if I'm supposed to be 2.5" under POA at 25 yards?

Is that 100 yard zero? If so, is it correct that at 50 yards I should be 1.25" under POA?
independentrider1
07-01-10, 20:23
I dont know the answer to that but with that ammo zeroed at 25 yards you would have a far zero of 275 yards. meaning if you are dead nuts at 25 yrds your sights (without adjustment) are dead nuts for 275 yards.
13grandy
07-01-10, 20:58
this seems like simple math... at least removing drop from the equation... so zero at 25 zero is 275 zero again with drop... that's including drop, which adds another dimension to the formula.... lemme see what I can find with that math added in....thanx
nickdrak
07-01-10, 21:32
With a 100yd zero you should be approximately 1.5" low at 25 yards.
Molon
07-01-10, 21:46
Anyone know what the effective zero of a 5.56 55gr M193 round would be if I'm supposed to be 2.5" under POA at 25 yards?



If you're point of impact is 2.5" below point of aim at 25 yards, the bullet will never even cross the line of sight. It will be approximatley 3.75" low at 100 yards.
Molon
07-01-10, 21:54
I dont know the answer to that but with that ammo zeroed at 25 yards you would have a far zero of 275 yards. meaning if you are dead nuts at 25 yrds your sights (without adjustment) are dead nuts for 275 yards.

False. A 25 yard near zero with M193 fired from a 16" barrel will produce a far zero that is beyond 380 yards.


http://www.box.net/shared/static/58uvxq0yei.jpg
orionz06
07-01-10, 22:07
misread OP...
Complication
07-01-10, 22:15
Anyone know what the effective zero of a 5.56 55gr M193 round would be if I'm supposed to be 2.5" under POA at 25 yards?

Height-over-bore for standard AR-15s is 2.6", if I recall. So to be shooting 2.5" below POA at 25 yards, you've got to be shooting nearly parallel to the sights.

Molon's right. With that zero, you'd have to shoot up-side down to ever have POA=POI.
JSantoro
07-02-10, 00:38
Anyone know what the effective zero of a 5.56 55gr M193 round would be if I'm supposed to be 2.5" under POA at 25 yards?

The answer is "ineffective," unfortunately.

Nose around these a bit; you'll see some data regarding different zeros and what they can do. You'll see many advocate for doing a 50yd zero and the reasons behind it.

https://www.m4carbine.net/showthread.php?t=54081

https://www.m4carbine.net/showthread.php?t=34671
NCPatrolAR
07-02-10, 00:45
Question answered