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Posted: 1/17/2011 4:28:25 PM EDT
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Have a M-16 that won't run full auto have changed firing pin and put in a new hammer spring.
You my get 4-5 rounds in the auto position then you have to recharge and will fire 1-2 rounds then you have to recharge it. There is a small dent in the primer and its not enough to fire it have used several different brands of ammo. do you have any ideas? This is a very early model built in 64 or 65 given to the Army.. |
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Agree that it sounds like it might be a bolt-bounce thing going on. Given the age of the lower, are you running with the original buffer spring? It might have weakened enough to allow the bolt to bounce. Do you have another AR that you can swap out the buffer spring to test my theory? Even better is if your spare AR (hpefully) has a H1 (heavier) buffer that you can also try. Good luck, and keep us posted. |
| Check the timing of the sear. Use a feeler gauge or equivalent to be sure that the sear does not trip before 0.10" measured between the face of the bolt carrier and the barrel extension. 0.12" is too early. 0.08" is too late, but will work only slowing down the cyclic rate. It is harder to fix then diagnose because the combination of fire control parts can effect it and that is the fix, swaping parts until the sear trips at the right time. Use a drill bit or allen wrench to measure. |
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Quoted:
Try a heavy buffer sounds like bolt bounce. it most likely is bolt bounce I have some question and possible solutions: Which kind of stock do you have on it A1, A2, or Telescoping? To prevent bolt bounce you have to do two of the following, use a new/stiffer/stronger buffer spring or use a heavier buffer. It is probably the buffer spring is worn down with a gun being that old. Just be sure to get one for the type of stock you have installed. I believe TonyK mentioned one time that he replaces all springs, trigger, hammer, detent, and buffer springs every 5,000 rounds or so. If that doesn't work then it could be a gas issue, and you need to inspect the Bolt Carrier around the gas key and the gas rings on the bolt. Also look for signs of gas escaping on the front sight post or gas block area where the gas tube is pinned at. |
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Quoted: Check the timing of the sear. Use a feeler gauge or equivalent to be sure that the sear does not trip before 0.10" measured between the face of the bolt carrier and the barrel extension. 0.12" is too early. 0.08" is too late, but will work only slowing down the cyclic rate. It is harder to fix then diagnose because the combination of fire control parts can effect it and that is the fix, swaping parts until the sear trips at the right time. Use a drill bit or allen wrench to measure. +1 |
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