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Posted: 5/29/2009 12:53:40 PM EDT
Would this amount of gap be normal? Gap measure .021", new install 20" Bushmaster barrel on an Armalite A2 upper. Have not fired with new barrel installed, rifle on flat surface, supported by rear A2 sight. Thanks.
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Everything hooked up right, I have never really thought about the sight alignment before. I positioned it based on the "test" I read in another post and this was the result. Not sure if this is "good" relative to what others have had. Installed using correct vise componants, upper receiver block, armor's tool. Just curious....
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You know the rear sight isn't level with the upper? So that "test" means nothing. As long as you are within 10 clicks of windage, I wouldn't worry about it. When I assemble an upper, I get it within 4 clicks but that requires a bit of precise clamping of the upper receiver and barrel. Why? The threads on the upper respond to the barrel nut torque by "clocking". Unless both the barrel and the receiver are firmly clamped, clocking happens. The USMC method of "mallet" adjustment can settle clocking but I prefer to prevent it in the first place. |
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Quoted:
You know the rear sight isn't level with the upper? So that "test" means nothing.
As long as you are within 10 clicks of windage, I wouldn't worry about it. When I assemble an upper, I get it within 4 clicks but that requires a bit of precise clamping of the upper receiver and barrel. Why? The threads on the upper respond to the barrel nut torque by "clocking". Unless both the barrel and the receiver are firmly clamped, clocking happens. The USMC method of "mallet" adjustment can settle clocking but I prefer to prevent it in the first place. That makes sense, thank for the info! 
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