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Which aperture do you use?

Discussion in 'Rifle Country' started by halfded, Apr 14, 2010.

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Which aperture do you use on your BUIS?

  1. The large one

    26 vote(s)
    50.0%
  2. The small one

    26 vote(s)
    50.0%
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  1. halfded

    halfded Member

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    Just wanted to see which aperture was preferred on BUIS.
     
  2. Broken11b

    Broken11b Member

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    All of mine have the 0-200 night aperture and the 25-300 daylight aperture, I keep it on the 0-200 aperture if I have to use it, the night ap works for most engagements and since i usually keep them deployed up and just focus on the red dot, the wide ap is easier to ignore until I need it.

    way I see it, if your using it for competition or defense, the 0-200 is faster and can be used in low light, the smaller aperture is near useless in lowlight or for speed.
     
  3. Ragnar Danneskjold

    Ragnar Danneskjold Member

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    I have an Army issue version of the BUIS which only have the small aperture. It's also what I've always used on my issue M4. So it just feels more natural on my AR-15.
     
  4. Broken11b

    Broken11b Member

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    Ragnar, which version did they issue you, the ones I had to use were crap.
     
  5. desidog

    desidog Member

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    I was issued crap as well.

    I figure the day sight is MOA, and the night sight is MOM.

    /Minute Of Man
     
  6. possum

    possum Member

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  7. DMK

    DMK Member

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    Both.

    On some of my carbines I use a Same Plane aperture from XS sight systems (no elevation change when switching from the small 'peep' sight to the larger "ghost ring").

    On other rifles I have the smaller 'peep' zeroed at 50y/200m and flipping to the large ghost ring gives me an approximately 100y zero. (I've sifted through a number of apertures in my parts drawer to find ones that work this way).

    With an A2 sight that has the elevation wheel, you can calibrate it and can then adjust the wheel so that you can use either aperture at whatever range you wish.


    For quick snap shots at close range (under 25-50y), I use the ghost ring. For 50y+ precision shooting, I flip to the smaller aperture.
     
    Last edited: Apr 15, 2010
  8. DMK

    DMK Member

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    Keep in mind that different standard AR15 apertures have varying elevation changes when flipping from one aperture to another.

    http://www.xssights.com/faqs.html#faq4
     
  9. Sediment

    Sediment Member

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    Da beeg wun.
     
  10. Bartholomew Roberts

    Bartholomew Roberts Moderator Emeritus

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    I use the Santose IBZ with my A2 sights and use the small aperture for above 300m/precision/day and the large aperture for moving/low-light.

    For my Troy folding rear sights, I have a same plane aperture and zero at 50yds. This puts me within 2.5" of point of aim out to about 250yds with 55gr M193. I just hold about 8" high at 300yds to make hits with irons at that range. I typically don't use irons outside that range unless I am just screwing around, so that works for me. Same principle, use the small aperture for precision/day and the large aperture for moving/light
     
  11. Zach S

    Zach S Member

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    The large one on my .22 and 9mm. The large one on my 5.56 as well, but it has an EOTech with absolute co-witness.
     
  12. TeamPrecisionIT

    TeamPrecisionIT Member

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    I use the big one as intended and the little one when the range is beyond 300m.

    Damian
     
  13. Quentin

    Quentin Member

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    Like Bartholomew Roberts, I normally use the IBZ with the small aperture. And the large one for low light conditions. Haven't moved on to optics since the A2 sights are so good.
     
  14. halfded

    halfded Member

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    Maybe I should have been more specific.

    First, BUIS means Back Up Iron Sights, you A2 guys don't apply here, sorry.

    Second, I was referring to BUIS that only have windage adjustment and aren't same plane, of course. Lower 1/3 co-witness should be thrown in the mix too.

    So, basically if you were stuck with ONE aperture for a BACK UP sight, which would you choose. I guess the poll's kinda screwed now.
     
  15. DMK

    DMK Member

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    Which BUIS are you thinking of?

    Most have a standard A2 aperture which flips between a close range ghost ring and a smaller 'peep' sight that is set a little higher for a longer range zero.

    Like was said earlier, it is usually recommended to zero the small peep with a Santos IBZ (50y/200m zero, giving you +/- 2" out to 250m) and you can flip to the larger aperture for closer range zero, low light, and/or wider field of view.

    Of course, you could swap the A2 aperture for an earlier A1 type aperture which has two smaller peep sights at two different elevations. Or an XS Same Plane if you want the same zero for both apertures.


    I'm the only one on the thread that mentioned an elevation wheel, and I just brought it up as an alternative for those with fixed carry handles.
     
    Last edited: Apr 16, 2010
  16. halfded

    halfded Member

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    Doesn't work that way. I have my A2 sight zeroed (per IBZ) with the small aperture at 8/3-2. In order to be on target at the same range with the large aperture, I have to go to 8/3. That's in increase in elevation, meaning that if you left the setting the same the rifle would shoot lower at the same range, and even lower than that at shorter range. The only way what you said would work is if you zero on the large aperture and use the small aperture for close range. Doesn't make any sense to do it that way though.

    The BUIS I'm using is from Samson MFG, sold from Del-ton and Spike's.
     
  17. DMK

    DMK Member

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    Yes.

    You had to increase the elevation on your wheel to make up for the lower elevation of the large aperture. Col Santos mentions that in his IBZ instructions.


     
  18. halfded

    halfded Member

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    ...Which means I'd be shooting lower than with the small aperture...

    Which means
    is incorrect.

    But the discussion of elevation adjustments is a digression here. I'm going to have one aperture to use without sighting in the gun over again, and just want some opinions on which to use. I know what IBZ is, I know the intended purpose of both apertures, and I know that there are same plane sights.

    My sight has 2 apertures and no elevation adjustment; it flips up with the large aperture in place (no choice).
     
  19. DMK

    DMK Member

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    OK, here's an example of the elevation shift. If I zero at 200m with the small peep, the bullet will also cross at 50y or so. It's an arc right? If I now shoot a group at 100y, it will be about 1.5" high, it's going up towards it's peak. Now, I flip to the ghost ring and shoot a group at 100y. It will be very close to zero and it's at the peak of its arc already. It's not going up anymore from there. Now if I shot at 200y with the larger ring, I'll be about 2-3" low. If I flip to the small peep, I'll be about zeroed and won't be 2" low until about 250y.

    But anyway, that is not the point of your thread.

    You say you have a regular A2 flip aperture with no elevation wheel. When you raise the BUIS, it comes up with the larger ghost ring in place. OK, I have the same setup on my carbines with ARMS #40s.

    Option #1 You can zero the large aperture at whatever you wish your battle zero to be (aka: PBR or Point Blank Range). A 200m or 200y zero is usually recommended, but that's your choice. When you flip to the small peep, you will have a zero at some longer range. You'll have to test it to see what that is. It will vary from one sight to another (see XS FAQ above). Shooting a group at 100y with the small peep and plugging your result in a ballistic calculator should give you an answer.

    Option #2 The way I do it is zero my longer range peep at my favorite PBR and accept that the larger ghost ring will not be zero'ed the same. In my experience it does shoot lower. At under 100y, being off an inch or three isn't going to matter that much. At longer range, your error expands in a cone shape. If I do my part, the smaller peep and known zero gives me a higher probability of an accurate hit at longer ranges.

    That is the only two choices you have unless you get the same plane aperture.
     
    Last edited: Apr 16, 2010
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