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Posted: 8/21/2011 3:27:24 PM EDT
| Just got myself a used m16a1 complete upper, put it on a lower I've always been using. I took it out to the range a few days ago and it worked fine. Took it out today and it would not cycle, everytime I'd fire I would have to manually charge the gun to get the next round to fire, occasionally the bolt would get held up with the next round stuck halfway up the feedramp, denting the case and jamming the rifle. What gives?? Could this be related to the gas tube? Made sure everything was clean, lubricated, tried different ammos, different mags, same issue. I know its not the lower, I've always used this lower and its fine, even put a buddie's upper on it to make sure and it functioned fine. Every once in a while I managed to squeeze off a few rounds without it stopping but for the most part it would not function. |
| I dont have the upper in front of me but its a Colt A1 upper with a colt CMP pencil barrel. I have the correct buffer/spring assembly in an A1 rifle buttstock, the lower works just fine with other uppers. I use the same bolt carrier and lower with a carbine upper, carbine stock and it works just fine. This m16a1 upper worked fine the first day I took it to the range, then the second time I took it out I had the issues, I dont know what happened between the two trips that would create this problem. |
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Quoted:
I dont have the upper in front of me but its a Colt A1 upper with a colt CMP pencil barrel. I have the correct buffer/spring assembly in an A1 rifle buttstock, the lower works just fine with other uppers. I use the same bolt carrier and lower with a carbine upper, carbine stock and it works just fine. This m16a1 upper worked fine the first day I took it to the range, then the second time I took it out I had the issues, I dont know what happened between the two trips that would create this Edit due to retardation Just to be sure I would scour the chamber with something aggressive and see if that helps. |
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It's not that complicated. If you have to manually cycle the weapon, the bolt is not getting gassed. As long as you don't have to use extreme force to dry cycle the weapon, it is a gas issue.
If you cannot find any leaks, take a brush and some solvent to the bore and give some extra attention to the gas port area. Make sure the gas block is not canted or loose, and pull the gas tube and check it for obstructions. Also check the gas key for obstructions, like a blown primer or casing shard. |
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Quoted:
Quoted:
I dont have the upper in front of me but its a Colt A1 upper with a colt CMP pencil barrel. I have the correct buffer/spring assembly in an A1 rifle buttstock, the lower works just fine with other uppers. I use the same bolt carrier and lower with a carbine upper, carbine stock and it works just fine. This m16a1 upper worked fine the first day I took it to the range, then the second time I took it out I had the issues, I dont know what happened between the two trips that would create this problem. The mismatch in ramps might make it jam, but not the extraction issues. Did you use the same ammo and mags? Im sure somebody with more experience will get it figured out for you. Just to be sure I would scour the chamber with something aggressive and see if that helps. There is no mismatch in ramps, m4 feed ramps did not even exist when any of these parts were manufactured. I tried different ammo types and different mags, and scrubbed the chamber VERY well. I am thinking there must be some type of obstruction in the gas tube. |
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Quoted:
Quoted:
Quoted:
I dont have the upper in front of me but its a Colt A1 upper with a colt CMP pencil barrel. I have the correct buffer/spring assembly in an A1 rifle buttstock, the lower works just fine with other uppers. I use the same bolt carrier and lower with a carbine upper, carbine stock and it works just fine. This m16a1 upper worked fine the first day I took it to the range, then the second time I took it out I had the issues, I dont know what happened between the two trips that would create this problem. The mismatch in ramps might make it jam, but not the extraction issues. Did you use the same ammo and mags? Im sure somebody with more experience will get it figured out for you. Just to be sure I would scour the chamber with something aggressive and see if that helps. There is no mismatch in ramps, m4 feed ramps did not even exist when any of these parts were manufactured. I tried different ammo types and different mags, and scrubbed the chamber VERY well. I am thinking there must be some type of obstruction in the gas tube. Yes sir. Try a fresh gas tube but check your bolt carrier group for a primer stuck in the gas key. Run a pipe cleaner into the gas key and it should show up quick. If not the bcg gas key, just swap a fresh gas tube 
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