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Posted: 11/24/2008 1:40:11 PM EDT
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Built a m4gery for my son.
Took it out to sight it in. Got it pretty well sighted in, got through maybe 20 or 30 rounds with no problem then started getting an odd ftf/eject problem. The gun would jam, and what we would see is that the empty case is still in the upper, jammed up against the top, with bolt jammed against the empty case. The next round has fed, but obviously is going nowhere. The empty case is not a stovepipe its still lined up with the barrel. I don't think its a gas problem because the BC has gone back far enough to feed (half feed) the next round. It started doing this fairly regularly. When we got home we stripped the bolt. Apart from the extractor claw being a bit sharp, there was nothing at all odd. There were a few brass shavings around - probably from the sharp extractor claw. I put a d-fender in, and we will go try again at the weekend. I am suspecting that somehow the brass shavings were interfering with the ejector claw, and the case was slipping out of its grasp too earl. Any other ideas? |
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The brass shavings could be interfering with the ejector. The extractor, from your description, seems to be working.
Place a drop of lube on the ejector, and work it in by exercising the ejector a few times with an empty case, or small pin punch. Ensure the ejector moves freely, and springs back out under spring tension. |
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To add, Pull all the way back on the charging handle and look at the front of the bolt .
The front of the bolt should not retract back past the back edge of the ejection port (should stop about 1/4 to 3/8" in front of the back of the port, but still behind the bolt catch. If the bolt does retract back past the back edge of the ejection port, then on ejection, the case can be deflected back into the action. If this is the case, get back to us on the stock type, and we can advice from there. |
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For anyone interested:
We took the gun out to the range again yesterday. After cleaning the bolt and installing a d-fender it worked flawlessly. I am betting on either * The extractor claw not fully engaging the rim because it is too sharp (fixed by d-fender), or * Brass shavings from the sharp claw gumming up the movement of the claw. Anyway, it seems to be fixed now. |
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