AR15 front post adjustment: How far down is too far?

[JesterRock]

I will be attempting to zero in my 16" AR 15 this week. When adjusting the front post, how far is too far when screwing it down to raise the POA? I became curious about this when today I could only utilize 15 yards inside my garage to use the laser, and I had to lower my front sight quite a bit to get it right. I will zero it in at 50 yards in the next few days, and I know that because of the difference in 15 yards and 50 yards I will be raising the front sight a bit. I kept the rear elevation at the lowest possible setting at 6/3. Attached are the photos of the front sight, and I was just curious as to how low is too low? Also, am I right in that you should keep the rear elevation at 6/3 (lowest possible setting) when attempting to zero in the rifle? Thanks for any input.

 

[FlyinBryan]

yes, the rear should be all the way down when you zero.

im not sure you can lower the front sight low enough to zero the rifle @ 15yds, but i might be wrong, ive never tried that.

as far as how low can you go with the front, i would say you can lower it as far as it will go, but i dont know. i dont see what it would hurt to lower it all the way if needed.

i guess ive been lucky. mine were spot-on when i gott-um.

 

[gotigers]

http://ar15zeroing.com/

If you have a FSB and an A2 style rear (fixed or carry handle) the above link will put you very close. I just sighted in a new AR the other day. After following the above instructions, i was very close to zero when i first shot it. YMMV.

 

[sugarmaker]

Typical starting point is to level the base of the sight post with the gas block. screw your rear sight all the way down, then come up 3 moa (however many clicks that is on your gun) to account for dead clicks and allow you to adjust for light conditions.

The next thing is zero the gun at 200 yards using your front sight for elevation adjustments, not using the rear elevation. Don't touch the front sight after that.

 

[4thPointOfContact]

You're using a laser bore sighter?
Due to the height between the barrel and the sights, the angle that is needed to intersect the two becomes much, MUCH more pronounced at short ranges.
Imagine how much of an angle you would need if you wanted to sight on something 10 feet away.. you'd probably have to elevate the rear (or depress the front) a matter of feet, if not just inches.
Even at 25 yards, most people sight about 1.5 inches below the intended Point of Aim. If you use the current sight picture, you might be shooting over the head of the target when you shoot at 25.

 

[john5036]

The next thing is zero the gun at 200 yards using your front sight for elevation adjustments, not using the rear elevation. Don't touch the front sight after that.

He could just zero at 50 yards, like he said he was going to do.

OP: Stick to the AR15zeroing.com link, and choose one of those methods. If you have access to a 25 or 50 yard rifle range, you might consider putting front sight back to mechanical zero for now until you actually shoot the gun or use the laser at the correct distance that'll coincide with your elevation knob.

Your elevation knob exists for very good reason, and the methods in the link will keep the guesswork out of you shooting at any distance up to 600.