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Posted: 11/15/2008 2:16:05 AM EDT
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I bought a new complete RRA AR in .223 and had scope sighted in with no problems. Installed a floating hand guard using Brownell's action vise and proper wrench to remove barrel nut.
Now at 40 feet with the scope mechanically zeroed the rifle is shooting 14 inches to the right and I run out of windage adjustment 4-6 inches before I can get the rifle zeroed in. Took the floating handguard off and reinstalled it. It is still doing exactly the same thing - shooting 14 inches to the right. What could be causing this? Thanks for the help. |
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check the easy things first....check your scope mount. I'm assuming that you took it off to work on the upper.
if that doesn't do the trick, take the barrel nut off and clean the mating surfaces. It only takes a tiny bit of dirt/debris to throw your barrel off by a degree or 2––and it sounds like yours is off by at least that much. remember to torque the barrel nut 3x (torque, back off, torque, back off, final torque) so the barrel is seated correctly. If you use anti-seize or otherwise lube the barrel nut, don't get any on the mating surfaces––just the threads. 30-80 foot pounds of torque according to the manual. |
Sounds like your barrel indexing could be off. Most likely happened from your FF HG installation.
To correct this, you’ll have to loosen your barrel nut, align your front and rear sights vertically (ensure the rear sight is at mechanical zero), and have someone hold the FSB steady as you torque the barrel nut. I like to use a piece of paper with a plumbed vertical line drawn on it, taped to the wall, across from my bench vice. I line-up this vertical line through the center axis of the bore, the rear sight aperture, and the FSP. 
I have a second person hold the FSB steady, against the direction of barrel nut torque, as I tighten the barrel nut. I recheck my vertical axis, and if necessary, repeat the process. Using this procedure has given me windage adjustments as little as 3-4 clicks during zeroing. |
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Hey QUIB––quick question for you: Not arguing––you obviously know what you're talking about––just trying to learn something.
Since the OP is using his scope and not the irons, if the barrel isn't indexed correctly, will this push the bore out of alignment? I only ask because I had a FAL that was about 5 degrees under-timed....it wouldn't hit paper at 30 yds with the irons' windage maxed out, but the scope was pretty close to mechanical center. When I corrected the barrel timing, the scope only took a few clicks to re-zero, and the sights lined up to near mechanical center too. |
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Quoted:
Good point, and one I over looked when I responded.
Hey QUIB––quick question for you: Not arguing––you obviously know what you're talking about––just trying to learn something. Since the OP is using his scope and not the irons, if the barrel isn't indexed correctly, will this push the bore out of alignment? I would think that a rifle with only a scope and no iron sights installed, could be zeroed in regardless of how the barrel is indexed. And this brings up another question: Are scope rings being mounted, one on the receiver, and one on the HG? |
| I got a complete upper from BM a while back. I had the exact same issues as the OP due to an over-torqued barrel that was canted. I could not zero the rifle no matter how far I adjusted the windage on the scope. I sent back the upper and it was fixed for free. |
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