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Posted: 10/11/2009 10:17:20 AM EDT
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Noob with a problem.
Ok here's the background. I sent my 20 in. HBAR Colt to gunsmith and had the A2 reciever swapped for a flat top and put La Rue 13 inch rails on it. I sent it out to have the work done because I didn't have the tools and I was afraid of screwing up my first rifle. The other day put my front and rear BUIS on it and noticed something didn't seem right. Upon closer inspection, it looks to me like the flat top reciever isn't lining up with the rail. Here's a pic. 
I swear they are off by like a millimeter. I haven't shot it yet, but won't this totally screw things up? Or am I just being really picky? Does this look wrong to any of you? If so, what do you think the problem is and how do I fix it? Any help greatly appreciated. Thanks in advance. |
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I had this issue a while back.
http://www.ar15.com/forums/topic.html?b=3&f=118&t=453930 The barrel nut was in fact over tightened. Get a gunsmith to retorque the barrel nut and it should solve the problem. Can't tell which side you rail is misaligned, but your barrel nut may not be tight enough. |
| For me I really need to see it from the rear to see how far off it is. One of mine is slightly off and took a couple of clicks of windage to zero (one line to the left on the Troy BUIS scale) and it's fine unless you look at the scale you really can not tell. Take it out and zero the BUIS and see if it is even off and how much then decide what to do. |
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This sucks.
I may try figure this out myself as there are not many gunsmiths that work on AR's in my state. What pisses me off is I went by the online reviews of this guy thinking that the work would be good. Now it's hassle. Thanks for your input. I'm read through that other thread. |
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Not gunna lie, I installed mine myself.
Mines off by a very tiny bit just like yours. I tried a couple different times to get it right. Got it closer but still not 100% perfect. My rear sight is cranked pretty far right, but is zeroed. Functionally it works perfect, maybe one day Ill break it down and fix it. I would try and zero it before trying to fix it, bc it is a PITA |
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Quoted:
Not gunna lie, I installed mine myself. Mines off by a very tiny bit just like yours. I tried a couple different times to get it right. Got it closer but still not 100% perfect. My rear sight is cranked pretty far right, but is zeroed. Functionally it works perfect, maybe one day Ill break it down and fix it. I would try and zero it before trying to fix it, bc it is a PITA Yeah, I'm gonna go to the range and zero it first. At least I know I'm not alone. Thanks for all your help. |
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Quoted:
Noob with a problem. Ok here's the background. I sent my 20 in. HBAR Colt to gunsmith and had the A2 reciever swapped for a flat top and put La Rue 13 inch rails on it. I sent it out to have the work done because I didn't have the tools and I was afraid of screwing up my first rifle. The other day put my front and rear BUIS on it and noticed something didn't seem right. Upon closer inspection, it looks to me like the flat top reciever isn't lining up with the rail. Here's a pic. http://i376.photobucket.com/albums/oo207/ketsy_photo/closeup.jpg I swear they are off by like a millimeter. I haven't shot it yet, but won't this totally screw things up? Or am I just being really picky? Does this look wrong to any of you? If so, what do you think the problem is and how do I fix it? Any help greatly appreciated. Thanks in advance. How about sending it back to the gunsmith? It's off, btw.. You can see it is. |
Yes, the lines of the rails are parallel, when they should align. Possibilities: 1. Upper is machined out-of-square, forerail is square. 2. Upper is machined square, forerail is out-of-square. 3. Both are machined out-of-square. 4. Both are machined square. 5. Forerail is turned too-short, or too-much. Try putting a bubble level cross-ways (perpendicular) to the length of the UPPER rail and view from the font or rear of the rifle and ensure bubble is centered. Then, without moving rifle, move the bubble level to the forerail, to see which direction it is tilted in. |
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Check the other end of the rail, is the barrel centered like it should be.
I've had to mess around with LT and DD rails both to get them exact. Usually after a couple re-instalations you can get it pretty close. I have swapped barrel nuts, even uppers. I've even messed with it to get the rear sight that much closer to centered. We have these "continous upper" rails now, and it is even more noticeable with them. And you can't really use them like a true continous rail upper. That's why I prefer the LT and older style DD rails. Receiver, big ass barrel nut, rail. |
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the barrel nut can be adjusted ever so slightly to fix this.
Simple, but a little time consuming and takes a vise and nut wrench. Adjust it looking very closely to get the gas tube perfectly centered in the hole. then put the rail on and inspect carefully.. repeat as necessary. With patience you can get it perfect. |
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