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Posted: 11/19/2012 10:49:48 AM EST
Have you ever zeroed your red dot for a lower 1/3 system where the dot does NOT sit directly above/in-line the middle post on an FSB?
Link Posted: 11/19/2012 10:55:48 AM EST
Not sure what you're asking. By it's very nature, 1/3 means you can place the dot on teh tip of the FS post unobstructed.
Link Posted: 11/19/2012 10:58:40 AM EST
Originally Posted By MisterPX:
Not sure what you're asking. By it's very nature, 1/3 means you can place the dot on teh tip of the FS post unobstructed.


proper cheek weld would have a dot from a 1/3 cowitness above the FSB, not touching it. Again, it's not an absolute co-witness. My "zeroed" in dot, when looking through it, sits a little to the left of center from the middle bar on the FSB. I'm wondering what could be off here.
Link Posted: 11/19/2012 12:18:07 PM EST
Your irons are zeroed in as well I presume?
Could just be where your head is, since most good RDS will let the dot float around and still be on target.

Place your rifle down, and aimed with irons at a point on the wall, look through the dot, if the dot is on that same target, then move your head around so teh dot floats, should still be on that same target point.
Link Posted: 11/19/2012 1:00:53 PM EST
Link Posted: 11/19/2012 6:39:39 PM EST
Originally Posted By MARSH1:
Originally Posted By sribble1:
Have you ever zeroed your red dot for a lower 1/3 system where the dot does NOT sit directly above/in-line the middle post on an FSB?


At what distance are you seeing the dot off from the irons. All will have some parallax shift at short distances. That might be what you are seeing.


Sorry, not in shooting the weapons as in sighting them independently. The red dot is above the fsb as is appropriate in a 1/3 cowitness view but is also slightly left of the middle post of the W shaped fsb.
Link Posted: 11/19/2012 7:38:59 PM EST
Originally Posted By sribble1:
Originally Posted By MARSH1:
Originally Posted By sribble1:
Have you ever zeroed your red dot for a lower 1/3 system where the dot does NOT sit directly above/in-line the middle post on an FSB?


At what distance are you seeing the dot off from the irons. All will have some parallax shift at short distances. That might be what you are seeing.


Sorry, not in shooting the weapons as in sighting them independently. The red dot is above the fsb as is appropriate in a 1/3 cowitness view but is also slightly left of the middle post of the W shaped fsb.


So when you say "above the front sight" do you mean if you are looking through the rear peep sight? If this is the case than the red dot should sit EXACTLY on top of the front sight post (touching). Now, if you mean that the red dot is centered in the window and you are not looking through the rear sight, than yes, it should be a little above the front sight post. Either left or right of it is just because of where you're holding your head.

Again, to be sure, if you look through your iron sights and your red dot is not absolutely on your front sight post (whether its in the lower third of the sights's window or the middle or wherever, really), one or the other is not sighted in
Link Posted: 11/20/2012 5:29:00 AM EST
[Last Edit: 11/20/2012 5:30:08 AM EST by topgunpilot20]

Originally Posted By sribble1:
Originally Posted By MARSH1:
Originally Posted By sribble1:
Have you ever zeroed your red dot for a lower 1/3 system where the dot does NOT sit directly above/in-line the middle post on an FSB?


At what distance are you seeing the dot off from the irons. All will have some parallax shift at short distances. That might be what you are seeing.


Sorry, not in shooting the weapons as in sighting them independently. The red dot is above the fsb as is appropriate in a 1/3 cowitness view but is also slightly left of the middle post of the W shaped fsb.

That's normal. All of mine are like that.

The difference is due to zeroing the irons without the optic, then inserting the optic into the visual plane causing extremely minor distortion (almost non-existent for practical purposes). Also, your eyes see and line up irons a tad differently than the RDO dot which can also cause a slightly different zero. This is why I tell people that adjusting a new RDO to the already-zeroed cowitnessed irons will get you extremely close, but the RDO will still likely need some fine tuning.

Make sure to zero your irons the same way you plan on using them. If you will use them without the optic then zero them that way, but if you will use them through the mounted RDO then zero them through the optic.
Link Posted: 11/20/2012 11:57:53 AM EST
Originally Posted By Will816:
Originally Posted By sribble1:
Originally Posted By MARSH1:
Originally Posted By sribble1:
Have you ever zeroed your red dot for a lower 1/3 system where the dot does NOT sit directly above/in-line the middle post on an FSB?


At what distance are you seeing the dot off from the irons. All will have some parallax shift at short distances. That might be what you are seeing.


Sorry, not in shooting the weapons as in sighting them independently. The red dot is above the fsb as is appropriate in a 1/3 cowitness view but is also slightly left of the middle post of the W shaped fsb.


So when you say "above the front sight" do you mean if you are looking through the rear peep sight? If this is the case than the red dot should sit EXACTLY on top of the front sight post (touching). Now, if you mean that the red dot is centered in the window and you are not looking through the rear sight, than yes, it should be a little above the front sight post. Either left or right of it is just because of where you're holding your head.

Again, to be sure, if you look through your iron sights and your red dot is not absolutely on your front sight post (whether its in the lower third of the sights's window or the middle or wherever, really), one or the other is not sighted in


yes, the rear folding sight is down, and I look through the back of the optic to find that the dot is slightly left of the middle post of the FSB. I had zeroed the dot to a 2.5 inch spread at 100o yards, but there was a slight left to right wind that day. I'm wondering if the windage had be pull the dot a little left to then have POI right where I wanted it.
Link Posted: 11/20/2012 12:00:05 PM EST
Originally Posted By topgunpilot20:

Originally Posted By sribble1:
Originally Posted By MARSH1:
Originally Posted By sribble1:
Have you ever zeroed your red dot for a lower 1/3 system where the dot does NOT sit directly above/in-line the middle post on an FSB?


At what distance are you seeing the dot off from the irons. All will have some parallax shift at short distances. That might be what you are seeing.


Sorry, not in shooting the weapons as in sighting them independently. The red dot is above the fsb as is appropriate in a 1/3 cowitness view but is also slightly left of the middle post of the W shaped fsb.

That's normal. All of mine are like that.

The difference is due to zeroing the irons without the optic, then inserting the optic into the visual plane causing extremely minor distortion (almost non-existent for practical purposes). Also, your eyes see and line up irons a tad differently than the RDO dot which can also cause a slightly different zero. This is why I tell people that adjusting a new RDO to the already-zeroed cowitnessed irons will get you extremely close, but the RDO will still likely need some fine tuning.

Make sure to zero your irons the same way you plan on using them. If you will use them without the optic then zero them that way, but if you will use them through the mounted RDO then zero them through the optic.


Yes, I plan to use them independently. And what you say makes sense except all pf the visual depictions of the 1/3 cowitness has the dot in line with the very middle of the FSB middle post and a little high of it due to the 1/3 cowitness vs. absolute...
Link Posted: 11/20/2012 12:41:26 PM EST

Originally Posted By sribble1:
yes, the rear folding sight is down, and I look through the back of the optic to find that the dot is slightly left of the middle post of the FSB. I had zeroed the dot to a 2.5 inch spread at 100o yards, but there was a slight left to right wind that day. I'm wondering if the windage had be pull the dot a little left to then have POI right where I wanted it.

The dot will move around slightly depending on the position of your head. If your irons are zeroed to the same distance, the dot will be right on top of the FSB post. You need to flip the rear folding sight up, and you will see that the dot will line up.
Link Posted: 11/20/2012 12:58:21 PM EST
Originally Posted By Captain_Morgan:

Originally Posted By sribble1:
yes, the rear folding sight is down, and I look through the back of the optic to find that the dot is slightly left of the middle post of the FSB. I had zeroed the dot to a 2.5 inch spread at 100o yards, but there was a slight left to right wind that day. I'm wondering if the windage had be pull the dot a little left to then have POI right where I wanted it.

The dot will move around slightly depending on the position of your head. If your irons are zeroed to the same distance, the dot will be right on top of the FSB post. You need to flip the rear folding sight up, and you will see that the dot will line up.


Yes, when the rear BUIS is up and the smaller aperture is flipped, the red dot from this now absolute cowitness is left of the middle post on the FSB. And, no every diagram has it as needing to be above or in-line. Does wind affect 100Y zeroes with 55 grain .223?
Link Posted: 11/20/2012 1:35:17 PM EST
Originally Posted By sribble1:
Yes, when the rear BUIS is up and the smaller aperture is flipped, the red dot from this now absolute cowitness is left of the middle post on the FSB. And, no every diagram has it as needing to be above or in-line. Does wind affect 100Y zeroes with 55 grain .223?


Depends how windy. THat said, based on your new info, either your irons or your dot is not prperly zeroed. Go shoot again, and find out which one is off.
Link Posted: 11/20/2012 4:31:08 PM EST
Originally Posted By MisterPX:
Originally Posted By sribble1:
Yes, when the rear BUIS is up and the smaller aperture is flipped, the red dot from this now absolute cowitness is left of the middle post on the FSB. And, no every diagram has it as needing to be above or in-line. Does wind affect 100Y zeroes with 55 grain .223?


Depends how windy. THat said, based on your new info, either your irons or your dot is not prperly zeroed. Go shoot again, and find out which one is off.


Yep. thanks for confirming
Link Posted: 11/20/2012 4:58:02 PM EST
It could be slightly off and still be zeroed. It is probably due to the way people line up irons differently or the way the dot appears. You should zero both on the same day and with the same ammo if possible to confirm.
Dustin
Link Posted: 11/20/2012 6:43:28 PM EST
Originally Posted By pezboytate:
It could be slightly off and still be zeroed. It is probably due to the way people line up irons differently or the way the dot appears. You should zero both on the same day and with the same ammo if possible to confirm.
Dustin


have you seen zeroing disparity between different 55 gr .223 loads?
Link Posted: 11/21/2012 5:20:07 AM EST
Even from batch to batch of the same brand the zero could be off. If I switch ammo types I try and confirm my zero if only for peace of mind. You never know really. The wind could be a cause too if there was a left to right wind when you zeroed the irons and a right to left wind when you zeroed the red dot it could be off a bit.
Dustin
Link Posted: 11/22/2012 1:59:52 AM EST
Try a 50 yard zero. Easier to zero irons and your dot at this distance and is a better zero for targets 0-300 yards (slightly low inside of 50yards, zeroed at 50, 1.5" high at 100, on at 200 and 8" low at 300 (hold on neck for center mass hit). Use a large enough target that will allow you to have a good sight picture when zeroing your irons. I like a 6" orange circle. I line up my irons and touch the bottom of the target with my front sight post. I find this is easier than holding center of the circle. I zero so poi is where the front sight touches the bottom of the target. I then move my dot so it is sitting on top of the front sight post while lining up my iron sights. This will put the dot close to the same poi as the irons. Now shoot to fine tune zero for dot. Hope this helps.

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