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Posted: 1/13/2010 3:24:16 PM EDT
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I was at the range today and the guy next to me was shooting a Colt. Not sure exactly which model. It was an older model(he said) with an A1 upper but had an M4 type adjustable stock and pencil barrel. He said it hadn't been shot all the much and had bought it from someone else. Perhaps an early 70 model?
Anyway he mentioned he was getting a lot of feeding problems. I offered to watch as his explanation wasn't that great. Every few rounds he would get a FTF(fail to feed) it appeared. The spent round would eject but the bolt would not go into full battery for the next round. The bolt locked up about halfway in the ejection port. Initially I had assumed the next round was jammed but that was not the case. The round simply was loose in the forward part of the action. You could jiggle the gun and possibly get the round to fall out. I had him give me the gun and sure enough the BCG was actually stuck in this position. I could pull the charging handle back until it grabbed the BCG and gently put the BCG back slightly and slowly let it forward again until it got hung up on something again at the same position. I did this several times trying to figure what it might be hanging up on. On one of the attempt I felt something give(so to speak) and the BCG felt free after that and would go all the forward into battery. We pulled the BCG from the upper to see if anything appeared abnormal. The bottom of the BCG and the top of the hammer, etc appeared to have more than normal wear and had areas where the finish had been worn off but not gouged. It later happened again while he was slowly playing with the charging handle and when it gave with him I could see the trigger give slightly. Appears the BCG was rubbing against the upper part of the FCG. I'm not all that experienced with ARs yet although I have assembled one lower so far so I at least have a basic knowledge of how things work. This guy didn't appear to know much about ARs or shooting in general. He also had been shooting a 243 to sight it in and didn't seem to know much about that either. I recommended he take it to someone who knows ARs and have a look at it. The gun itself didn't look all that old but it appeared to possibly be a frankengun so not sure if the guy may have gotten a bad deal or not. |
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Sounds like the firing pin is slightly too large in the collar.
If you mix a M16 firing pin into an AR15, the larger firing pin collar catches on the hammer. Look to see the firing pin collar does not protrude beyond the edge of the bolt carrier, if it is slightly sticking out, it can hang up on the hammer. Also look at the firing pin retaining pin,,,is it beat up or bent? |
| Funny you mention that about the firing pin. Seems to me when I was looking at it the firing pin seemed to extend further out than seemed normal. I do not have access to this gun anymore. I didn't know this guy so will probably never see it again. I mostly posted for some hints just in case I see this again. |
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Quoted:
If it happens when it's time for the bolt to lock u I would say that the bolt wasn't lubes properly and it was not rotating to lock Nope, the above posters have it: the firing pin collar is too large, and the hammer is catching it when the B/C moves forward. In the above case, only the tip of the bullet has just started to enter the barrel extension itself, while the face of the bolt is still way back in the ejection port behind the live round rim. |
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