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Posted: 2/28/2005 5:12:02 AM EDT
| What exactly is a slam fire and how does it happen? |
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Nam and 1IV's descriptions sound kind of confusing and maybe even contradictory. They're not; they each described a different cause of slam fires. In general, a slam fire is when the weapon fires as the bolt closes. It can be caused by a stuck firing pin (in which case you could have a runaway fire situation-effectively full auto with no control), or by a failed disconnector or hammer allowing the hammer to go forward as the bolt closes. The hammer type of slam fire is less common, and is controlable by simply letting go of the trigger. Also, a hammer slam fire kind of depends on all the proper conditions being present; the hammer spring has to be slow enough to not ride the bolt carrier forward-which would not result in enough force on the firing pin to cause the weapon to fire-but fast/strong enough to impart enough energy to the firing pin to cause it to strike the primer hard enough. A stuck firing pin can be caused by dirt in the bolt, crud in the bolt carrier, or a bent or otherwise distorted pin. It's a good idea to inspect the firing pin every time you clean the rifle to make sure that you have a chance to notice a distortion before it causes a problem. And I'd always make sure to clean the firing pin space in both the bolt and carrier every time, too. |
| You can also eventualy get a slam fire on an AR by rechambering the same round over and over as the free floating firing pin makes contact to the primer every time the round is chambered.Over time it will eventualy go off from being constantly hit and thats in a clean rifle.There was a thread here about it I think it was some thing like a round that was rechambered more than 20 times and it finaly let off and this was in the army I belelive,happened in Iraq. |
If a slam fire is dangerous (other than from being at the business end of the weapon) then why is an M231 not dangerous to the firer. It fires from an open bolt, does not have a hammer, and fires once the bolt closes and the firing pin then exerts pressure on the primer. It has a very high rate of fire. I thought the slam fire was only dangerous because of the possibility of a accidental discharge, not because it could it could fire out of battery, and harm the firer. Otherwise how come the M231 doesn't fire out of battery? It's basically "slam firing" all the time. So does a thompson SMG. It doesn't even have a firing pin, just a nipple on the bolt face, yet it doesn't fire out of battery, the primer doesn't detonate until the round is seated in the chamber and then there is enought pressure for the firing "nipple" to detonate it. I also was issued an M60 a few years ago that broke its sear (disconnector), and would fire uncontrollably until you broke the ammo belt to stop it feeding. But it wasn't firing out of battery, it just wouldn't stop once you released the trigger. |
The potential danger is to those who don't know what it is. If you knew that's the way the gun was supposed to work, you could take that into account when using it and not place yourself in a dangerous position. It's dangerous to have slamfires in a weapon you don't expect them in. |
That what I thought, the danger of a ND or AD. |
+1 If you look real hard at the AR/M16 bolt/carrier assembly, you'll notice that the firing pin CAN'T contact the primer until the bolt is locking into the barrel extension. If the firing pin is stuck, it will set the primer off now. Not really safe, because it is a defacto full-auto and the locking lugs may not be fully engaged, creating a possible weakness. WIZZO |
| I've experienced it at the range on my buddies AR. It had cheap (read JUNK) fire control parts and the disconnector was letting the hammer go as the bolt came forward. At first it just doubled, then I fired again and it let off a 7-8 round burst. Once I took it apart, I could actually grab the hammer with my thumb and forefinger while holding the trigger to the rear and pull it free from the disconnector with almost no effort. Definitely not safe and the DNR range officer wasn't impressed to say the least. Replaced the FCG with all new parts from Bushmaster and have had no problems since. Using quality parts in your lower and regular cleaning will probably prevent most occurrences of a slam fire. |
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