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Posted: 12/30/2008 8:12:30 PM EDT
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My friend just picked up a colt A3 with a HBAR. He brought it over to let me see it. He had a sightmark holo on it and a flip up front sight. Well anyways when I was looking down the rail with the front sight up I noticed that the front sight was canted. After closer look it appears that whoever he bought it from put a quad rail gas block on and it was loose. I could also see carbon around the barrel where the gas block was placed on the firearm.
Well I asked him if it was short stroking and he said it did it twice in the seven rounds he fired. I told him probably because the gas block was not secure. On the bottom side of the gas block was two allen set screws. Now here is what I need to know. What could be another reason the gas block would be canted if the screws are secured. Also I didn't think the A3 came factory with quad gas block and a HBAR. I advised him not to work on it unless he knew what he was doing. Or take it to the gunsmith. Let me know what you guys on here think. 
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Pencil mark the gas block against the barrel shoulder, and note if the gas block is tight against the barrel shoulder on not.
Now using an old allen wrench, insert the wrench into the one of the screws and use a torch to heat up the wrench only to transfer heat down to the screw alone ( +700* to break the loctite bond). Now pull the allen wrench and do the same to the other screw to break the bond. With a new allen wrench after the flash suppressor has been pulled, loosen the gas block screws and pull the block off the barrel. At the barrel port hole, you will have a round burn mark. If the burn mark is centered around the barrel gas port, then the gas block was installed correctly. If the burn mark is not centered, then when the gas block is reinstalled, it will need to be correctly indexed to center the burn around the hole. Note: the gas block passage is larger than the barrel port hole, and the block larger hole is showing up as the burn. Once the gas block is reinstalled (FS as well), remove the bolt from the carrier and drop only the carrier in the upper to confirm that the gas tube is correctly indexed to the carrier key. If needed, correct the alignment of the tube to key. If any of this is beyond yours/his skill level, then it's time to take the rig to a smith. |
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Quoted:
My friend just picked up a colt A3 with a HBAR. He brought it over to let me see it. He had a sightmark holo on it and a flip up front sight. Well anyways when I was looking down the rail with the front sight up I noticed that the front sight was canted. After closer look it appears that whoever he bought it from put a quad rail gas block on and it was loose. I could also see carbon around the barrel where the gas block was placed on the firearm. Well I asked him if it was short stroking and he said it did it twice in the seven rounds he fired. I told him probably because the gas block was not secure. On the bottom side of the gas block was two allen set screws. Now here is what I need to know. What could be another reason the gas block would be canted if the screws are secured. Also I didn't think the A3 came factory with quad gas block and a HBAR. I advised him not to work on it unless he knew what he was doing. Or take it to the gunsmith. Let me know what you guys on here think. 
So is this a "Colt" factory problem or a problem with an aftermarket modification? |
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