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Posted: 7/17/2004 10:19:38 AM EDT
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My model 1 upper has started to FTEj 1 out of 7 rounds. I've tried different mags with no success. The spent round ends up being pinched by the bolt when the bolt closes. The neck of the case is facing outward, away from the gun while the rim of the spent case is inside the chamber. A live round is fed into the chamber. I've noticed that when the gun is cycling properly the spent cases seem to be ejecting less uniformly than usual. The gun has only 600 rounds through it. I'm shooting m193. Thanks! |
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Extractor is dropping the case before the end of bolt stroke. To confirm this, install a #60 O ring around the extractor spring to see if the problem goes away (will add tension to the spring). If this band aids the rifle to make it work, then order a new Extractor spring to fully correct the problem (and pull the O ring band aid). Note: Fixed since I was watching the ending of "End a of days" and typing at the same time. Be thankfull it wasn't the "L Word during one of the good parts. HM, Thanks for the catch. |
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No dice. I got the #60 O Ring, slipped it over the extractor spring, and it's still leaving the spent case in the chamber. The extractor does not have any obvious signs of wear or damage. I'm thinking the ejector spring may not be strong enough. Am I correct in assuming that since the bolt is traveling far enough back to pick up a fresh round I do not have a bolt travel problem? The ejector seems to have a strong spring but I have nothing to compare it to. You can't push it in with your finger, but a punch pushes it in rather easy. |
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By the numbers, The ammo is fired, and the barrel gas is directed to the carrier/bolt to unlock the bolt. The case is pulled out of the chamber, and travels back with the bolt to the end of the rearward stroke. Once the bolt/ buffer bottom out on the back of the receiver extension, the buffer acts like a dead blow hammer and stalls the bolt out at back of travel. At this point, the spent case is deflected off the bolt face and pivoted to the 5:00 position. Trouble-shooting should start as follows, 1. Does the bolt lock back after the last shot out of the mag. If yes, then the bolt is full stroking so we can move on. If not, then you need to check the gas rings and the key to confirm that the allen screws are still tight. 2. The rear of the bolt face does not retract father than the front of the ejection port. You can test this by manually charging the action and seeing where the buffer bottoms out. The bolt should be stopped at least 1/8” in front of the back of the ejection port, if not, then the case can be deflected back into the action. 3. The weights in the buffer are free moving. To confirm this, just take the buffer out and shake it. If the buffer is not working, then the case does not have enough time to pivot off the bolt face, and is thrown forward with the forward movement of the bolt. This can cause the case rim to be danced off the front of the ejection port and be caught by the forward movement of the bolt. 4. A weak ejector spring can cause ejection problem. If weak, the case is not truly pivoted off the bolt face during buffer end of travel stall, and again ejected on the forward stroke of the bolt. Also, if the ejector passage hole or ejector has a bur, it can cause delays in ejection. Best to just pull the ejector and spring, and check them and the ejector passage out for fouling or a bur that may have broken off and is causing problems. Note: HP shooters will clip coils on the ejector spring to make the rifle eject forward. To many winds clipped will cause ejection problems. 5. The only wear on the extractor is at the front of the outside edge, and not at the rear pivot point. There was a post a while ago with an ejector that had wear on the pivot point. This means that the bolt channel in the carrier limits the ejector grip on the spent case rim (return pivot). This cause the spent case to be spit out of the chamber due to barrel pressure, but the extractor is never in real control of the spent case. Also, when you have the ejector out of the bolt, put the extractor back on the bolt and inset a round on the bolt face. The extractor should retain the case. If the case falls off, then the contact pad on the extractor needs to be lowered to allow it to cam father into the center of the bolt face. Post back once you have gone threw the checklist and let us know if you have found a glitch in the system. |
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1) The bolt catch has not yet failed to catch the bolt, although I've only ran the mag empty a couple of times since this problem has started. The gun jams every 7 rounds or so. 2) The bolt stops 1/8" in front of the back of the ejection port. 3) The buffer rattles when you shake it. I never shook it (or any other) before, so I don't know if it is normal. 4) I haven't been able to disassemble the ejector yet. I'll get to that tomorrow. |
| You should have a complete spare bolt anyhow. Ya might just order one and swap, see if that fixes the trouble if so strip down the bolt and replace all springs, extractor and such. Also are your gas rings properly staggered? I dont know what happens if the gas rings are worn out as I've never had any problem with it. |
Yeah, I think I'll try to pick up a spare bolt and carrier at the gun show this weekend. I don't have any spare parts. Trouble shooting ARs is a breeze with a second unit to swap parts with. Hummm, maybe I've got a good excuse to get a complete upper. I finally got around to working on the AR again today. I removed the ejector and found a very small piece of metal in the ejector's groove. I think this may be the culpret. I've got a spring on order but I don't know if I'll get it by this weekend. I might just try it with the clean ejector and the factory spring. I'll keep ya'll posted. Thanks again for all the quality suggestions, tips and facts! |
Just curious, what happens if the rings do have gas leakage? I've never experienced a problem in this area. What happens if they fail? |
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Crap! Carried the AR out today and it still has the same problem. It did jam less often however. So maybe the ejector recess is still a little dirty. I replaced the ejector and its spring earlier. Oh yeah, I tried loading only one round in the mag at a time to see if it would fail to lock the bolt back. The bolt never failed to lock back but I did end up with an empty case backwards in the chamber with the bolt locked back one time. Seems like I saw a thread with a similar condition earlier. I've got the bolt soaking in Bore Scrubber [again] and I'm considering ordering a new extractor spring from Wolff. Buying a spare bolt is sounding more like a good idea every day. edited to add: I did notice that some of the brass is getting ejected in a forward direction, some rearwards, and some just seem to fall out of the chamber. Real erratic. |
I have nothing to compare it to as I am an AR newbie. It feels like a strong spring to me. You can't push it in with your finger. I can hold the bolt in my hand, place a spent cartridge in it, and the ejectorwill fling it out with some authority. Both the old ejector spring and the new one come from Model 1. |
Yep. It sure does. This could be a source of ejector hang up, no? I let the bolt soak all week, I've put it back together, and I'm carrying it out for a function check this weekend. My new extractor spring is not in yet. I'll keep you posted. Thanks again. |
| My AR ran fine today. Must have needed that extra bit of cleaning in the ejector housing.hinking.gif |
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