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Posted: 5/25/2008 4:09:15 AM EDT
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Shooting at 50 yards I have my rear sights turned all the way to the left and the rifles still shoots right 3 inches. It's an older Olympic I bought used. It had a A1 upper and when I bought it I noticed the rear sights were turned all the way to the left also. It shot to the right that way also. I changed out the upper to a flat top and put a carry handle on it but it didn't help the problem. Could it be the front sight housing is slightly canted? |
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To add to Quib, Shotgun the upper open and look at the center of the barrel feed lugs against the center of the take down lug. If the barrel slipped in the upper barrel socket during install, the bottom/center of the feed lugs will not be centered on the front take down lug. At this point if you do find this, options are to either remount the barrel, or just slip the "entire barrel" in the upper barrel socket with the barrel nut still tightened via a leather mallet (will not mar) strikes to the FSB just above the barrel while holding only the upper receiver. |
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To add graphics and expand a bit on Dano’s post: Barrel indexing is the barrel assembly and FSB being inline with the upper receiver and centered rear sight. All four components should line up with each other after torquing the barrel nut. (My red index line is slightly off and exaggerated in the INCORRECT illustration below, but I think it still gets the point across.)  Often times when the upper receiver is placed in the vice block and secured in the vice, the barrel assembly slips within the upper receiver in the direction of torque. This will result in excessive windage during zero.  When I torque barrels I use the assistance of a second person to hold the FSB against the direction of torque until the barrel nut is aligned correctly for gas tube installation. Hope that helps clear things up. Quib |
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Before I forget: Another possibility is that the barrel to receiver indexing is correct, but the FSB to barrel indexing is off. This occurs during FSB installation at the factory. But most often in the case of barrel swaps, it’s usually the barrel indexing to receiver that is the culprit. |
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Nice pictures QUIB. Thanks for all of the helpfull information... Regards, Rodster71 Here |
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