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Posted: 5/6/2015 12:03:29 AM EDT
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Is there a way to check the alignment of the barrel in relation to the upper?
Joe |
| I'm actually looking at the axial alignment. Long story short,. My friend brought his bushy to a gunsmith to have the regular front sight replaced with an adjustable gb. After a few hours the gunsmith called and said that they tried and tried but can't get the flash hider off so they'll have to cut it off. Well the problem is that the flash hider on the 14.7in barrel was pinned......fast forward to the range and with his scope back on his rifle is shooting 8 moa low. I'm wondering is something is out of wack. |
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Removing and replacing the scope, unless it is a QD and the exact same slots were used each time, can account for some, if not all of the difference. If it is a fixed mount, changes in torque of the mount nuts can also affect impact. Also, a different flash hider could change the barrel harmonics, its inherent vibration while the bullet passes from the chamber through the barrel until it exits the muzzle, enough to change point of impact, often significantly.
If the rifle shoots as well, and the scope can be adjusted to rezero without getting too far away from its mechanical zero (physical midpoint of its elevation travel), I would not worry about it. |
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Quoted:
Removing and replacing the scope, unless it is a QD and the exact same slots were used each time, can account for some, if not all of the difference. If it is a fixed mount, changes in torque of the mount nuts can also affect impact. Also, a different flash hider could change the barrel harmonics, its inherent vibration while the bullet passes from the chamber through the barrel until it exits the muzzle, enough to change point of impact, often significantly. If the rifle shoots as well, and the scope can be adjusted to rezero without getting too far away from its mechanical zero (physical midpoint of its elevation travel), I would not worry about it. This, I wouldn't worry about it. Using the same scope with the same zero, I was about 6" off at 50 yards when going from a DD RIS II to a Geissele Mk4 (also swapped perm attached muzzle devices). Same barrel, upper, BCG, and gas block. My question is, if it took them that long to figure out his MD was pinned/welded, did they pin/weld the new one? |
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Yes the hider was properly installed. But back to my original question..........."Is there a way to check the alignment of the barrel in relation to the upper? " If they "tried and tried" to get the pinned divice off without first drilling or cutting it, yeah, they could have screwed it up. And if they removed the barrel first, as they should have, that would also be cause for it to have lost zero. Honestly, I wouldn't be too worried if you have faith in the Smith who did the work. I don't think there is a way to check alignment of barrel to upper. You would have to either run a rod down the barrel or remove it and roll it to check concentricity. |
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Take a bubble level and set it on the upper receiver, and have it go down and above the barrel. At several points down the barrel, measure from the bottom of the bubble level to the top surface of the barrel at each particular point being measured. Write down the measurement for each spot being measured.
Now for each spot that's being measured; measure the diameter of the barrel for that spot, and each successive spot. For the measurements found , divide each one by 2. Write down the numbers you get after being divided. Now, for each spot add the measurement you found from the bottom of the bubble level to the top surface to the diameter of the barrel for that spot after it was divided. The added up dimensions for each spot should end up the same. |
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Take a bubble level and set it on the upper receiver, and have it go down and above the barrel. At several points down the barrel, measure from the bottom of the bubble level to the top surface of the barrel at each particular point being measured. Write down the measurement for each spot being measured. Now for each spot that's being measured; measure the diameter of the barrel for that spot, and each successive spot. For the measurements found , divide each one by 2. Write down the numbers you get after being divided. Now, for each spot add the measurement you found from the bottom of the bubble level to the top surface to the diameter of the barrel for that spot after it was divided. The added up dimensions for each spot should end up the same. 
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Yes the hider was properly installed. But back to my original question..........."Is there a way to check the alignment of the barrel in relation to the upper? " You and your friend need to learn more about rifles. If it can be zeroed, then it doesn't matter. |
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You and your friend need to learn more about rifles. If it can be zeroed, then it doesn't matter. Quoted:
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" You and your friend need to learn more about rifles. If it can be zeroed, then it doesn't matter. Yes we do. That's why I'm asking questions.....And I guess it sounds like you'd be Ok with a distorted upper reciever as long as " it can be zeroed". |
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Yes we do. That's why I'm asking questions.....And I guess it sounds like you'd be Ok with a distorted upper reciever as long as " it can be zeroed". Quoted:
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" You and your friend need to learn more about rifles. If it can be zeroed, then it doesn't matter. Yes we do. That's why I'm asking questions.....And I guess it sounds like you'd be Ok with a distorted upper reciever as long as " it can be zeroed". If it shoots well and the scope is zeroed fairly close to its mechanical zero, this is convincing evidence that the receiver was NOT damaged. The normal variables I mentioned above account for the differences you are seeing. Only if you are running out of adjustment in the scope should you be chasing remote causes. Shoot the rifle for group. If it is the same as before and the scope zeroes easily, whatever problem you think you have is not a real problem. |
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Yes we do. That's why I'm asking questions.....And I guess it sounds like you'd be Ok with a distorted upper reciever as long as " it can be zeroed". Quoted:
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" You and your friend need to learn more about rifles. If it can be zeroed, then it doesn't matter. Yes we do. That's why I'm asking questions.....And I guess it sounds like you'd be Ok with a distorted upper reciever as long as " it can be zeroed". You seem pretty confident it's messed up. Sounds like you have your answer. Take it back. We are offering you what we know and you continue on... 
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