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Posted: 12/14/2008 10:51:33 AM EDT
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A friend of mine built his first ar15 (.223) and went to test fire it. This was his report:
Went and shot the AR today for the first time and was having a problem. It would not cycle a new round. It basically shot like a bolt action having to manually chamber a new round every time. I tried lubing it up but did not change anything. It doesn't even to be attempting to eject the spent cartridge. I was wondering if you knew what could be causing that. I don't know anything about AR's so I don't even know where to start to figure it out. I don't know if I can adjust anything or if there is something I can check on the assembly. Any help would be appreciated, let me know what I should do.
I think it might ether be a gas tube leak or bad gas rings. He has a bushmaster upper and im not sure of the bcg. Any help from you guys would be great. |
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Initially sounds like it's short stroking.
From Tweaks troubleshooting sticky at top of page: "––-TEST FIRING PROCEDURE––- -Unload the rifle and verify that it is clear. -Check the bore for obstructions. -Load the rifle with one round from the magazine. Use quality ammunition and a proven magazine for this. -Aim downrange and fire, the bolt should catch on the bolt stop. Hold the rifle as loose as possible. -Reload and repeat the process if the rifle does not lock open Depress the bottom of the bolt stop before firing this time. This allows for weak magazine springs, sticky followers, or an overly strong bolt catch spring. -If the bolt does not lock open then there is a gas system problem. Investigate and repair the problem. -If it only locks open with the bolt stop depressed, repeat the process with a different magazine. If the rifle still fails to function then look at the bolt stop as a probable culprit." Have your friend do this test and report on results. |
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Quoted:
Way, Way too much information missing to even try to figure out the problem. +1 My only guess would be to make sure that his bolt is in the carrier the right way. Maybe it's trying to eject the brass on the wrong side... But again, to agree with Dano, way too many variables still missing to put your finger on it. |
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Quoted:
A friend of mine built his first ar15 (.223) and went to test fire it. This was his report: Went and shot the AR today for the first time and was having a problem. It would not cycle a new round. It basically shot like a bolt action having to manually chamber a new round every time. I tried lubing it up but did not change anything. It doesn't even to be attempting to eject the spent cartridge. I was wondering if you knew what could be causing that. I don't know anything about AR's so I don't even know where to start to figure it out. I don't know if I can adjust anything or if there is something I can check on the assembly. Any help would be appreciated, let me know what I should do.
I think it might ether be a gas tube leak or bad gas rings. He has a bushmaster upper and im not sure of the bcg. Any help from you guys would be great. Did he build the complete upper? Including the gas block and tube? This part in red sounds like there is NO gas getting to the action. Did he install a gas tube!? If he somehow installed the gas tube upside down, difficult unless he bent it, that would do it. Mis-locating the gas block, i.e. not over gas hole will also do this. |
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Quoted:
Quoted:
Way, Way too much information missing to even try to figure out the problem. +1 My only guess would be to make sure that his bolt is in the carrier the right way. Maybe it's trying to eject the brass on the wrong side... But again, to agree with Dano, way too many variables still missing to put your finger on it. you're kiddin...right? Yea I probably jumped the gun a little bit but it kinda sounded like a short stroking symptom. |
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OK, I spoke to the member in question. He took it to the range today w/ another member and another AR. Upon further review, it actually WAS short-stroking, so they changed out the BCG, and the AR functioned fine w/ the other BCG installed. When they looked at the suspect BCG, they discovered a VERY loose gas key. Of course, no one had the proper size allen wrench, so he tightened it best he could w/ what he had. Yes, he was careful not to damage the screws. AR cycled fine on the next shot. Short stroked again after that, but by then it'd worked loose again.
So, his question now is, how tight to tighten the gas key screws, once he has the correct allen wrench? How to prevent this from recurring? Any other suggestions? |
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Quoted:
OK, I spoke to the member in question. He took it to the range today w/ another member and another AR. Upon further review, it actually WAS short-stroking, so they changed out the BCG, and the AR functioned fine w/ the other BCG installed. When they looked at the suspect BCG, they discovered a VERY loose gas key. Of course, no one had the proper size allen wrench, so he tightened it best he could w/ what he had. Yes, he was careful not to damage the screws. AR cycled fine on the next shot. Short stroked again after that, but by then it'd worked loose again. So, his question now is, how tight to tighten the gas key screws, once he has the correct allen wrench? How to prevent this from recurring? Any other suggestions? Tighten down screws to spec [or put new ones in if damaged, then torque] stake key properly, enjoy. |
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Pull the carrier key and clean both mating sides of the carrier and key before reinstalling the key back on. Regarding the old allen bolts, throw them away and install new ones. If they have already stretch, then you are just asking for one to snap, which is a worse problem to have to deal with.
The correct torque is 37 in lbs for the allen bolts, and his a link on how to stake the key correctly to keep the bolts from becoming loose again. http://www.ar15.com/content/page.html?id=122 |
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