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Posted: 1/18/2017 10:40:47 AM EDT
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have a question for anyone that can answer it. i tinker with ar's and my last three builds, while looking good, have a slight problem. using iron sights, on all three you have to crank the rear sight all the way to the right, and in some cases this isn't far enough. everything appears to "line up" correctly. up or down with the front sight, no problem, but left or right, seems like they are all way off to the left, forcing me to crank the rear sight way to the right.
what am i missing? any suggestions? any experience's 
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Quoted:
have a question for anyone that can answer it. i tinker with ar's and my last three builds, while looking good, have a slight problem. using iron sights, on all three you have to crank the rear sight all the way to the right, and in some cases this isn't far enough. everything appears to "line up" correctly. up or down with the front sight, no problem, but left or right, seems like they are all way off to the left, forcing me to crank the rear sight way to the right. what am i missing? any suggestions? any experience's
thanks How are you torquing the barrel nut? Cranking the rear sight full right yaws the barrel right. So for whatever reason, the upper receiver where the sight is mounted is too far left. How are you clamping the upper when torquing the barrel nut? When torquing the muzzle device? If you use an upper clamp when torquing the muzzle device, that's a long enough lever arm to cause problems. Supposed to use barrel blocks and clamp the barrel. |
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I bought a new Ruger 556 AR 15 carbine with the Ruger/MBUS magpul type flip-up rear sight and had to move the windage on the rear sight a good bit over to the right, but not all the way over. The proprietary Ruger front F-type FSB looks good and straight with the upper rial. However, I've gotten to where I like the quick-reflex red-dot sights better than the iron (or polymer in the case of the MagPul MBUS) sights for back yard plinking.
If your barrel nut is torqued correctly, you might try using the rubber hammer to wack the front sight a time or two in the correct direction to correct the extreme windage on the rear... I've never done it, but read about it. Good luck. |
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I bought a new Ruger 556 AR 15 carbine with the Ruger/MBUS magpul type flip-up rear sight and had to move the windage on the rear sight a good bit over to the right, but not all the way over. The proprietary Ruger front F-type FSB looks good and straight with the upper rial. However, I've gotten to where I like the quick-reflex red-dot sights better than the iron (or polymer in the case of the MagPul MBUS) sights for back yard plinking. If your barrel nut is torqued correctly, you might try using the rubber hammer to wack the front sight a time or two in the correct direction to correct the extreme windage on the rear... I've never done it, but read about it. Good luck. If that actually moves anything my intuition tells me the rifle is not assembled properly. Either the front sight/gas block is going to shift/bend, or if the upper receiver is clamped then the upper might bend. No way you're going to tweak a barrel with a rubber hammer. None of that sounds good to me. These things were designed to work perfectly after getting dropped on the ground and stomped on. See the videos and writeups of people torture testing buis. Smashing the rifle like a wood maul, trying to break the sight. No poi shift for Magpul plastic buis. If that didn't move stuff a rubber mallet shouldn't do anything. If it does then stuff isn't torqued/pinned/setscrewed right. The two I assembled had basically perfect sight alignment, the 5.56 I put Magpul Pro on were actually perfect windage right out of the box. I figured dumb luck since it was my first. Then the second one, 300blk, went together the same way. If OP has three in a row with the same sight issue this feels like an assembly problem or if it's the same brand/batch lower, a qc issue with the lower. |
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If OP has three in a row with the same sight issue this feels like an assembly problem or if it's the same brand/batch lower, a qc issue with the lower. However, in my research, I've read a lot about upper receivers being milled off center, or at least having the appearance of being milled off center, due to having more metal on one side of the upper receiver cut than the other. Some of my uppers exhibit this issue, although not quite as bad as the one in the pic. And, from what I've read, it is not a few uppers, but thousands, or even hundreds of thousands. Here is a pic of what I'm talking about... and, here is the AR15.com thread where I read the info. Off center upper receivers...This is an older thread, but this phenomenon with the uppers is still going strong today. I read that this is a common occurrence with the different forgings from different manufacturers, but it just doesn't seem right to me. I think this could cause the top rail on the upper to be slightly off-center with the barrel and FSB possibly causing sighting ussues. But that is just me. 
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Quoted:
Not sure, but I think you meant a QC problem with the upper receiver, and not the lower. However, in my research, I've read a lot about upper receivers being milled off center, or at least having the appearance of being milled off center, due to having more metal on one side of the upper receiver cut than the other. Some of my uppers exhibit this issue. And, from what I've read, it is not a few uppers, but thousands, or even hundreds of thousands. Here is a pic of what I'm talking about... and, here is the AR15.com thread where I read the info. Off center upper receivers...This is an older thread, but this phenomenon with the uppers is still going strong today. I read that this is a common occurrence with the different forgings from different manufacturers, but it just doesn't seem right to me. I think this could cause the top rail on the upper to be slightly off-center with the barrel and FSB possibly causing sighting ussues. But that is just me. http://i46.tinypic.com/2e1zsp0.jpg Holy cow I never saw that before! Yes, I meant upper. |
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Now people are becoming aware of how they can sell their stuff so cheap. Poor quality control and no reject standards. I was ready to buy a cheap PSA upper for use as a blaster rifle until I read this thread. Quoted:
Now people are becoming aware of how they can sell their stuff so cheap. Poor quality control and no reject standards. I was ready to buy a cheap PSA upper for use as a blaster rifle until I read this thread. Here is a quote from the Aero rep on the Industry forum regarding this exact issue... Originally Posted by Aero Precision:
A lot of what you are seeing with the differences in thickness are forging variances. I cannot speak for PSA but our machining process begins with the picatinny rail and every other operation is based upon the initial cut of the rail. The variances in forging sometimes provide more metal and optically it appears off center. I'm not saying that there aren't some bad ones that come out of the machines but we typically catch those. |
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