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Posted: 1/27/2014 9:19:07 AM EDT
[#1]
I've seen cam pins out of spec that would cause issues when the gun heats up, but never a complete lack of unlock. Is it physically hard/more resistent to cycle by hand when its hot?
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Posted: 1/27/2014 9:27:04 AM EDT
[#2]
Just a quick question. What kind of rifle is it and are the receivers aluminum or polymer?
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Posted: 1/27/2014 9:28:13 AM EDT
[#3]
No, I didn't feel an increase in resistance throughout. And I couldn't find any obvious signs of wear and it was still well lubed (slip 2000) after it degrades into "single shot mode".
The cam pin, is that the cotter pin on the side of the BCG holding the firing pin in place? A buddy of mine suggested that might be the problem and to check it for loseness but it feels snug and has resistance when pulling it out. |
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Posted: 1/27/2014 9:31:06 AM EDT
[#4]
Quote HistoryQuoted: No, I didn't feel an increase in resistance throughout. And I couldn't find any obvious signs of wear and it was still well lubed (slip 2000) after it degrades into "single shot mode". The cam pin, is that the cotter pin on the side of the BCG holding the firing pin in place? A buddy of mine suggested that might be the problem and to check it for loseness but it feels snug and has resistance when pulling it out. |
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Posted: 1/27/2014 9:36:03 AM EDT
[#5]
Quote HistoryQuoted:
No the cam pin is the pin that goes through the bolt and "cams" in the slot on top of the carrier. Quote HistoryQuoted:
Quoted:
No, I didn't feel an increase in resistance throughout. And I couldn't find any obvious signs of wear and it was still well lubed (slip 2000) after it degrades into "single shot mode". The cam pin, is that the cotter pin on the side of the BCG holding the firing pin in place? A buddy of mine suggested that might be the problem and to check it for loseness but it feels snug and has resistance when pulling it out. Ah, I'm not sure how to know if it's out of spec, but the top square portion does spin awfully easily, to me at least, like it's loose. I don't have another bcg to compare it to. |
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Posted: 1/27/2014 9:47:51 AM EDT
[#6]
Quote HistoryQuoted:
Ah, I'm not sure how to know if it's out of spec, but the top square portion does spin awfully easily, to me at least, like it's loose. I don't have another bcg to compare it to. Quote HistoryQuoted:
Quoted:
Quoted:
No, I didn't feel an increase in resistance throughout. And I couldn't find any obvious signs of wear and it was still well lubed (slip 2000) after it degrades into "single shot mode". The cam pin, is that the cotter pin on the side of the BCG holding the firing pin in place? A buddy of mine suggested that might be the problem and to check it for loseness but it feels snug and has resistance when pulling it out. Ah, I'm not sure how to know if it's out of spec, but the top square portion does spin awfully easily, to me at least, like it's loose. I don't have another bcg to compare it to. But reading up on what the cam pin does I don't think this is the problem. After the rifle heats up the bolt doesn't move back at all when fired, the whole bcg stays in place. If I then pull back on the charger the bolt comes back and the cartridge ejects normally. It appears to be a gas related issue |
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Posted: 1/27/2014 9:57:49 AM EDT
[#7]
Possibly worn gas rings...
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Posted: 1/27/2014 10:11:03 AM EDT
[#8]
Quote HistoryQuoted:
Possibly worn gas rings... Hmm, I did the stand it on end test and the bolt stayed in place. As I understand it that means that the rings are okay. I'll break it apart and visually verify them as well. Thank you |
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Posted: 1/27/2014 10:31:55 AM EDT
[#9]
Quote HistoryQuoted:
Hmm, I did the stand it on end test and the bolt stayed in place. As I understand it that means that the rings are okay. I'll break it apart and visually verify them as well. Thank you Quote HistoryQuoted:
Quoted:
Possibly worn gas rings... Hmm, I did the stand it on end test and the bolt stayed in place. As I understand it that means that the rings are okay. I'll break it apart and visually verify them as well. Thank you Broken rings can make it bind and pass the test as well. |
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Posted: 1/27/2014 10:34:23 AM EDT
[#10]
Out of spec barrel chamber? What type of rifle or upper is it?
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Posted: 1/27/2014 11:54:13 AM EDT
[#11]
its in the gas system
usually a gas block can expand, the gas key might leak a little, or gas rings lose too much. I would check the gas key, see if one of the screws has broken (only can tell if it twist or not) Gas block check the set screws if it has them, clean the block and look for leaks, do the gas ring check |
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Posted: 1/27/2014 12:37:49 PM EDT
[#12]
Quote HistoryQuoted:
Out of spec barrel chamber? What type of rifle or upper is it? Lower is a S&W M&P 15 alumnium. Upper is a JSE Surplus 16" HBAR |
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Posted: 1/27/2014 6:57:29 PM EDT
[#13]
I think I found the problem. I'm new to the AR platform and didn't know how to, or that I should, remove the bolt from the BCG. The bolt was sticking when I pushed it in and out with my fingers. Once I pulled the bolt out, scrubbed it and the interior of the carrier (which both had build up), then aligned, or more correctly misaligned the O rings, the bolt operates smoothly, it'll stand on end without dropping but it has a nice smooth movement instead of catching. I'm confident that the weapon will fire properly now.
Thanks to BB, drop11, TaylorWSO for your help |
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