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Posted: 6/29/2004 10:19:53 PM EDT
I am trying to implement the Santoz IBZ on my AR, but am having a problem. The rifle has a 20" heavy-barrel with a JP compensator, and I'm using Federal XM193 ammo. The rear-sight is this fixed DPMS rear sight: I did have some initial problems getting the anti-clockwise clicks that are needed for the new 200 yard elevation position; after slackening the 1/16" set screw, the elevation wheel didn't want to move at all. However, after attempting to move it clockwise (it still wouldn't budge) and then re-tightening the set screw in despair, I found that I had miraculously obtained some anti-clockwise clicks !! Whatever  . By trial and error, I managed to get the required 4 "half" clicks anti-clockwise, and I zeroed the rifle at 50 yards. So far, so good.With the elevation wheel in this new "200 yard" position, the rifle seems to be pretty much on at 200 yards (just tested on small steel plates so far). However (and here's the problem), when I dial the elevation wheel to the 300 yard position (3/6), my shots on a 300 yard target are impacting way high - maybe 12" or more above POA (again, an estimate, as I only checked so far on a steel plate). Does anyone have the faintest idea how I can fix this ? 
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Check to see that you have moved the elevation wheel the correct # of clicks below the 8/3 or 6/3 setting. There are two types of sights out there according to the IBZ procedure. Each requires a differnt # of clicks below the 8/3 or 6/3 marked setting. I believe it said that one type has 4 clicks between marked settings and the other has 6. When you get it set right the 'new' bottom position is good from 50 to 200 yds. Shabo |
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StealthyBlagga, Get it on paper at 25, Zero at 50, then don't touch it. I LOVE the IBZ, but you'll drive yourself crazy with all the +2, +4 and all that jazz. Been there and done that. Mathmatically, it works, no doubt. I just keep it simple. Leave it on 8/3 (or 6/3), Zero at 50, then leave it. If you want to know what your round is doing past 200, there are plenty of charts out there. Just round the numbers up or down so that you can remember them in you head, then you'll never have to worry about adjusting that rear sight when you're in a pinch. With my shorty, the rounds inpact at 50 and 200, in between, they are never more than 1.5 inches high. I'll never shoot to 800m, so I don't worry about adjusting the rear elevation, set screw, etc. Just my 2 cents. Do what works for you! AEM 3/75th |
| I have had similar troubles. I was able to shoot out to 500 yards and the A-2 stuff was way off. I recorded everthing on a piece of paper somewhere so I can just get a ballistics program on it and figure out how many clicks I will have to move my elevation drum. Its just a matter of me getting around to it lately. |
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I use this rifle for ISPC/3 gun shooting at almost any range between 0 and 500M, so a well-calibrated elevation drum is quite important. I'm going to re-zero using the GI method (300M+2 clicks up on my sight) then check how many clicks down I need for the 50/200yard zero. I'm also going to chrono the ammo today and see if I can get a handle on this problem via a ballistic calculator... watch this space. |
i shoot 3 gun and can't imagine ever using the elevation drum. its a timed event! you take a shot at something, see where you hit, and compensate. knowing where your gun shoots at those ranges beforehand makes it even easier. i do the 50 yard zero and never touch the adjustments again until i start missing! |
In 3-gun matches, stages can vary from close range (<100yds) up to 400yds or more. While I agree that changing the elevation setting during a stage is usually impractical, I would argue that setting the optimum rear-sight elevation should be part of your pre-stage preparation... if a stage has all its targets between 300 and 400yds, a 200yd zero is a poor choice because the front sight will obscure all the targets. Obviously, if everything is in the 0-250yd range, then the Santoz IBZ is the ideal choice, but in my case I can see a need for valid elevation adjustment, at least out to 500yds. Oh, and if you can really see your fall of shot on an IPSC paper target at 300yds, my hat is off to you. |
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I think it's no more complicated than this: Large aperture-elevation drum set to 8/3: Zero at 50 yards - this should be the same as a 200 yard zero with the large aperture. Switch to small aperture: Should be zero at 300 yards. Elevation ring ranges should track within a couple of inches to at least 600 yards - i.e. with the small aperture and elevation ring set at "5" you sould be close at 500 yards. |
OK, so I chrono'd the ammo through my rifle today and ran the numbers through a ballistic calculator. The results are shown below (yellow shows the zero-distances to the nearest 25yds): As the 200M zero POA/POI do no exactly coincide at 50 yds, I'm going to re-zero more carefully using these numbers and see if I can improve the accuracy of the elevation drum scale. I'll also check the true performace at the longer ranges with paper rather than steel. Worse case, I may have to ignore the elevation gradauations and do it like the NM guys (count the clicks). If I find anything Earth shattering, I'll post it here. 
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What? I thought you're suppose to use the small aperture when zeroing in at 50 yards, not the big one. groups.msn.com/TheMarylandAR15ShootersSite/improvedbattlesightzero.msnw |
Nope. I'm not talking about doing anything to the elevation knob except leave it set at 8/3. The large aperture is supposed to be used for distances from 0-200. If you zero the large aperture at 50 yards, you will be on at 200yards (see ballistic table posted above - 50 is -0.3 and 200(yards) is +0.6 - that's certainly close enough). Switching to the small aperture raises the Point of Impact so you are now (with the small aperture) zeroed at 300 yards without making any other adjustment. Dial up the elevation knob for distances beyond 300. Simple, huh? |
Yep you're using the 'standard 50 yard zero' as taught by several instructors. You don't dick with the small aperture or the elevation wheel. Just zero with the large aperture at 50yards. Its a simple zero intended for fighting carbines that won't be used beyond 200M. I've got a writeup on it that will be going up on MD-AR15.com for the Zeroing Methods section (when I get around to it).
As pointed out your problem is you didn't follow the directions. The DPMS is a full moa click so you should only have gone down 2 clicks to zero. As you went down 4 when you set the sight to 3 it was like setting the sight to 375M+ (thus the rounds that were high). Set the dial to bottom out at -2 clicks and rezero - you'll be much closer. Note however you will still be a bit high as the IBSZ was designed for 14.5" M4s with M855. It works fairly well for 20" rifles with M193 (good enough to keep it on a man sized target) but don't expect 'x ring' type results.
Two problems with this statement: 1) the GI method is 3 +1 click (not 2) at 25M 2) Using this method will give you a 10"-12" high trajectory at 300M. The +2 will work better at 25M or set it to '4' and shoot at 25 yards. |
I don't want to add to the confusion, but I am talking about a different method of zeroing, NOT the Santoz IBZ. The "standard 50-yard zero" is used from 0-200 with the large aperture and from 300 and beyond with the small aperture and the elevation wheel. I have found it to be simple and effective. YMMV. |
Isn't that what I said? |
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Sorry, YOU did not understand. I assure you my DPMS sight is a "half-click" version (that is, two clicks between the "3/6" position and the "z" 25yd GI zero position). Per the IBZ procedure, I verified that I have 6 clicks between the "3/6" and "4" positions, rather than the usual 3; this is why I (correctly) used double the normal number of clicks. There could be many causes for the discrepancy I am struggling with - please don't assume stupidity is one of them.
Lets not cover the "1 vs 2 click" issue again. Assuming I performed the GI 25M zero correctly, I would have expected to be much closer than I am at 300yds (the difference between yards and meters is not enough to account for the discrepancy I am seeing. Are you saying its normal to be this far out ? Thanks for your input. 
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Simple for short to medium range combat applications, but not for 3-gun/IPSC shooting out to 400yds or more... please remember, this rifle is a competitive tool, not a CQB carbine. For anything beyond 100yds, I really need the extra precision of the smaller aperture. This is why I like the Santoz IBZ. I just need it to work right 
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OK, I'm really trying to help - not get in a pissing contest. Let me understand what you want - you want to be able to use the small aperture at 300 yards with the elevation ring set at 3/6, right? OK, so why not set the elevation ring at 3/6 and zero your gun at 300? Having established that zero, then shoot at 200 and find out how many clicks down you need to come on your elevation knob - this will be your "200 yard" zero position on your elevation knob. Confirm this "200 yard" zero position by firing at 50 yards still using the small aperture. It's just a "backwards" Santoze IBZ, but since you have access to a 300 yard range, why not? Just a thought. |
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Gaijin Thanks for the quick feedback... I did not mean to offend. Your suggestion is a good one, and pretty much where I am heading if I can't get the "official" Santoz 50yd zero procedure to work right for me. Its just a pain to hike out to the 300yd line and back several times in the 110 degree heat we have out here at the moment.  I guess I'm mostly looking for an explanation as to why the Santoz procedure appears not to work in my case. I know its supposed to be a battle zero, but I would have expected to be closer at 300... am I expecting too much ? |
Assuming you performed the GI 25M correctley then YES I would expect the rounds to be 10-12" high. If you did the Santose IBSZ correctly then NO I wouldn't (and have not seen) results that were that far off. |
I'm using Federal XM193 (55grn FMJ). The measured muzzle velocity out of my rifle was 3326fps (mean of 5 shots). The tip of the front sight post is 2.5" above the center of the bore. To create the trajectory table/chart above, I assumed a BC of 0.255, a temperature of 100degF, humidity of 5%RH and altitude of 1000ft ASL (I live near Phoenix). |
Yes, the barrel is free-floated, and all shots were fired with the FF tube resting on a sandbag rest. The barrel was not touching anythig. I did not use a rear rest. |
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OK, take a deep breath. Everything with the small aperture. All distances in yards. All "clicks" on the rear sight elevation knob are assumed to be 1/2 MOA. 1. Set rear sight elevation knob 4 clicks below 3/6 setting 2. Zero at 50 yards 0.4" low - this will be 0.0 at 200 yards 3. Raise rear elevation knob 4 clicks to the "3/6" setting - this will be +0.5" at 300 yards (close enough) 4. Raise 6 more clicks to the "4" setting - this will be 2.8" high at 400 yards 5. Raise 8 more clicks to the "5" setting - this will be 8" high at 500 yards 6. Raise 10 more clicks to the "3/6" setting - this will be 16.8" high at 600 yards So, The markings on your elevation knob don't work perfectly for your gun and ammo combination. No problem. To be "dead on" at 400 yards - come up 4 clicks from the "3/6" setting and you will be 0.5" low at 400 To be "dead on" at 500 yards - come up 11 clicks from the "3/6" setting and you will be 1.25" high at 500 You can mark these on your elevation knob with a white paint marker. And if you're as OCD as I am, all the intervening clicks look like this: 1 click up from "3/6" - zero at 335 yards 2 clicks up from "3/6" - zero at 360 yards 3 clicks up from "3/6" - zero at 380 yards 4 clicks up from "3/6" - zero at 395 yards 5 clicks up from "3/6" - zero at 415 yards 6 clicks up from "3/6" - zero at 430 yards 7 clicks up from "3/6" - zero at 445 yards 8 clicks up from "3/6" - zero at 465 yards 9 clicks up from "3/6" - zero at 480 yards 10 clicks up from "3/6" - zero at 495 yards 11 clicks up from "3/6" - zero at 505 yards And so on. Let me know if this helps or just adds another layer of confusion. |
Wait, so did I zero my rifle in wrong the other day? This is my first AR. I went to the range, and zeroed in my LMT BUIS and EOTECH. I used the small hole, and got it zeroed. I have no idea how to use my elevation thingy. Dont know the calculations. When you're in battle, how do you figure out how far somebody is to adjust it? Anyways, should i go back and rezero with the bigger hole? |
The large aperture (bigger hole) is designed for use from close contact to 250 yards or so. The large aperture lets in more light (easier low light shooting) and results in faster target acquisition than the small aperture. The small aperture is designed for use from 300 yards and beyond. When using the small aperture, you can turn your rear elevation knob to get closer hits at extended ranges. If you will never shoot beyond 200 or so, and you do not plan on any low light shooting, some people prefer the small aperture as it results in an easier sight picture (smaller aperture, greater depth of focus, front sight is more in focus). If you are comfortable with the small aperture, leave it alone. Just remember that te small aperture and large aperture hit to different points of impact, so are not interchangeable. Clear as mud, right? |
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Yea, i dont plan on shooting past 200 yards, but you never know. Also, lets say when you zeroed in with the large hole, but switch to your small hole. Wouldnt you need to adjust your windage too, since the sight is on a screw, and it will move slight to the side? |
This is not true. Any observed windage difference between the small and large aperture is shooter error. Sorry, but true. |
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Forest/Gaijin: Thanks for the data and suggestions... I'll give these a shot and post my results here. HondaAccord: The centers of the big and the small apertures are at different heights. If you are never going to shoot beyond 200yds, you might want to try replacing your regular A2 aperture with a "same plane" rear aperture from XS which locates the centers of the big and small apertures at the same height... this way, you can zero for 200M using the Santoz IBZ and simply flip the apertures according to your needs (speed vs accuracy, low light etc.). |
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I prefer the small hole, because I can see better with it. The big hole, i have a hard time finding the center of it. But back to the Santoz IBZ. From what i'm reading on groups.msn.com/TheMarylandAR15ShootersSite/improvedbattlesightzero.msnw You're suppose to sight in using the small hole, or am I just reading it wrong? Step #6. Any other place that steps out the process? |
You are reading it right... zero using the small aperture. My issue is that, after following this procedure, my zero is incorrect at 300M (when dialed to the 3/6 position). From some replies here, this is apparently a "known issue". I'll post how I overcome this problem, when I get around to overcoming it. |
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