AR15 fired out of battery?
I had a problem today that is entirely new to me. I have been reloading for more than forty years and either from luck or just being careful have never had a similar problem.
This afternoon my AR15 appeared to fire out of battery. The case blew the primer and the primer hole is gone. The case extruded into the extractor cut in the bolt and generally looks like a belted magnum. The case didn't split or deform otherwise. The action is full of carbon but appears undamaged other than a bent extractor. I was able to open it by rapping the butt of the rifle on a carpeted floor. The rifle worked as it should have and the gas was vented through the magazine. The rifle had been cleaned before firing and thirty rounds had been fired when the problem occurred.
The load was a commercial case (sized and trimmed), a standard small rifle primer, a 55 grain spitzer bullet and 25.8 gr of H335. I have used this same load many times before and have not had any problems.
Any ideas about may have happened?
Edit: The rifle is an Armalite and was completely and cleaned and was functioning normally.
This afternoon my AR15 appeared to fire out of battery. The case blew the primer and the primer hole is gone. The case extruded into the extractor cut in the bolt and generally looks like a belted magnum. The case didn't split or deform otherwise. The action is full of carbon but appears undamaged other than a bent extractor. I was able to open it by rapping the butt of the rifle on a carpeted floor. The rifle worked as it should have and the gas was vented through the magazine. The rifle had been cleaned before firing and thirty rounds had been fired when the problem occurred.
The load was a commercial case (sized and trimmed), a standard small rifle primer, a 55 grain spitzer bullet and 25.8 gr of H335. I have used this same load many times before and have not had any problems.
Any ideas about may have happened?
Edit: The rifle is an Armalite and was completely and cleaned and was functioning normally.
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Sounds like one for nononsense... 0 -
Contrary to popular belief, its virtually impossible for an AR-15 gun TO fire out of battery.
The gun was designed that way on purpose.
The reason is that until the bolt is rotated into place and closed, the firing pin is held away from the primer and simply mechanically can't reach it. On other words, if the gun is out of battery, it can't fire.
I hate to point this out, but almost all alleged "out of battery" firings in AR-15 are due to faulty reloads.0 -
That does sound right Beantown. Is it possible that the firing pin was stuck in the fired position so that when the bolt started to rotate the pin hit the primer before the bolt entirely closed? The pin floats freely and there is not return spring like the one on a 1911 Colt. I don't know the answer and am trying to prevent this from happening again.
The rifle is an Armalite and was completely cleaned.
Hlouie0 -
When you say the rifle was cleaned before firing, do you mean that you completely disassembled the bolt & bolt carrier for cleaning, & that they functioned properly when reassembled?
And, by AR15, do you mean a Colt SP1? Or, do you really mean an AR-type rifle made by someone else?
Neal0 -
The carrier and firing pin are cammed away from the boltface until the bolt is rotated into battery.
Theoretically, if the cotter key were broken or missing, the bolt could come forward, leaving the firing pin slightly behind and when the bolt slams into battery, the firing pin can fly forward causing a slam fire.
Also check the key for wear. It is the key that keeps the firing pin away from the boltface until it is cammed into battery.0 -
quote:Originally posted by beantownshootah
Contrary to popular belief, its virtually impossible for an AR-15 gun TO fire out of battery.
The gun was designed that way on purpose.
The reason is that until the bolt is rotated into place and closed, the firing pin is held away from the primer and simply mechanically can't reach it. On other words, if the gun is out of battery, it can't fire.
I hate to point this out, but almost all alleged "out of battery" firings in AR-15 are due to faulty reloads.
This is not correct. The firing pin can reach the primer anytime the bolt comes in contact with the case head. What supposedly can't happen is the hammer can't reach the firing pin. As noted if the pin is stuck in the hole it WILL fire the case before the bolt is in battery. That is as it's slamming forward to load the cartridge nto the chamber. As mentioned in my third sentence the hammer can reach the firing pin with the lugs not fully seated. Due to the cam cut in the bolt carrier being slightly off. This isn't supposed to happen but it does. Those two things can cause an AR to fire out of battery.0 -
quote:Originally posted by sandwarrior
quote:Originally posted by beantownshootah
Contrary to popular belief, its virtually impossible for an AR-15 gun TO fire out of battery.
The gun was designed that way on purpose.
The reason is that until the bolt is rotated into place and closed, the firing pin is held away from the primer and simply mechanically can't reach it. On other words, if the gun is out of battery, it can't fire.
I hate to point this out, but almost all alleged "out of battery" firings in AR-15 are due to faulty reloads.
This is not correct. The firing pin can reach the primer anytime the bolt comes in contact with the case head.
Actually, I don't think this last statement is correct.
Contrary to the design of many guns, the AR-15 firing pin is NOT free to "float" until the bolt is absolutely locked into battery.
The reason is that there is a flange at the base of the AR-15 firing pin that engages the carrier and prevents forward motion of the firing pin until it is unlocked by the final rotation of the bolt.
See here:
And more importantly, here:
http://www.m4carbine.net/showpost.php?p=358709&postcount=99
Short of the final rotation that locks the lugs, the pin is blocked or mechanically retracted, and the only way the firing pin tip can reach the primer is if the pin or carrier are broken.
On the other hand, if a reload had a high (ie not fully seated) primer, then the primer could get "squished" by the closing action of the bolt before the lugs were locked. That could cause an out of battery discharge, though i think in fairness if that happened it would be properly classified as a reloading/ammo defect, rather than a gun defect.
quote:
What supposedly can't happen is the hammer can't reach the firing pin. As noted if the pin is stuck in the hole it WILL fire the case before the bolt is in battery.
As mentioned in my third sentence the hammer can reach the firing pin with the lugs not fully seated. Due to the cam cut in the bolt carrier being slightly off. This isn't supposed to happen but it does. Those two things can cause an AR to fire out of battery.
Several rifles are designed the way you describe, but I'm pretty sure the AR-15 isn't one of them.
Again, unless I'm completely off my rocker, the AR-15 pin is locked in place at its rear until the final rotation of the bolt carrier locks the lugs in place (and unlocks the firing pin flange).
While it may be possible for a defect to cause the hammer to fall before the gun is totally locked, even were that to happen, the firing pin still shouldn't move.
For the same reason, the firing pin tip can't get stuck through the bolt face unless its broken. I suppose that is possible, and in theory it could cause an out of battery discharge, though if this were the case, the broken pin should be obvious on disassembly of the rifle.0 -
The firing pin floats free. The flange on the pin is so the cotter key can keep it in the bolt carrier. I will say I exaggerated a bit when I said "Anytime the bolt head contacts the case." The bolt must actually be near the rear of it's movement, and the cam pin near it's rearmost movement, to fire out of battery. But it still doesn't prevent a stuck firing pin from slam firing a primer out of battery before the cam pin completely hits the back of the slot. There's a space in there where it can happen...and has. Also, the trigger (hammer, specifically) group is free to move within the slot provided for it to strike the firing pin. The bottom of the bolt carrier is supposed to keep it from hitting the pin. If the bolt is partially seated in the lugs and the bottom of the bolt carrier is short in any way, the hammer can reach the firing pin and fire a round. This is supposed to be technically "in battery". However, it's firing the rifle half out of battery. Which means everything happens faster and the case takes the brunt of it. I wouldn't say the round was not reloaded right until you did a full UNBIASED investigation of what happened.
FWIW, this was what was happening to me with my 6.5 Grendel. The hammer would just catch the firing pin while the bolt was half-locked in battery. It happened to me with the M16A1's I carried years ago. All the improvement in the rifle pretty much went to nothing. The ammo got improved. It wasn't as filthy. but it still operates on the premise nothing can go wrong. Let me tell you, with that rifle it does! They are accurate. But, they are finicky. If you don't believe me ask SOCCOM why they DUMPED it in favor of the SCAR?0 -
Sand Warrior is correct...the firing pin is free floating, and can reach the primer before the rifle is in full battery(bolt LOCKED). Beantown is also almost correct in that the firing pin can not reach the primer...untill the bolt is rotated ALMOST into full battery. By being almost into full battery, the bolt is still not locked up, and the bolt/bolt carrier will be able to violently return if it gets a full seal around the chamber, and the force of full pressure gas is able to be harnessed.
These are designed so the bolt is cammed closed, and when fired, the bolt does not move untill the pressures in the barrel has dropped significantly. Dropped to the point that it is almost equalized to the pressure of the gas returning in the gas tube. Actually...the force in the gas tube against the bolt carrier is what unlocks the rifle.
But the rifle will fire slightly out of battery. However, it will almost never slam fire as there is not enough enertia with the hammer riding the firing pin to do so...unless the firing pin is stuck in the forward posistion...or you accidentally got a pistol primer mixed in with your rifle primers.
Just be careful and get things checked out. If you are using a progressive press to load your ammo, or a powder measure to drop a charge, make sure part of the charge does not get hung up, and drop with the next one too...creating an overload.
Best0 -
HLOUIE2,
There is another scenario in this and in that mode Beantownshootah is correct. Headspace can be improperly set by the reloader. Headspace isn't usually ever the issue with new manufactured ammo. But, for the reasons described in my earlier post, if the case prevents the bolt from fully turning closed you can have a partial "out of battery" fire. I believe this was the case with my 6.5 Grendel (I hate admitting that[B)]). I had somehow inadvertantly not fully sized down the cases and the shoulder hit the front of the chamber and the bolt stopped rotating at that point...partially in the lugs. What happened at that point was when the rifle fired, the lugs took up the initial force of the discharge but then when gas came back through the tube it released the lugs and the case still had too much pressure in it. I noted when sizing the cases that some of them had a little shaved off ring from the base. I had never seen that before.
Bottom line is I was lucky in that it wasn't really far off and the bolt carrier didn't retract under full force...just more than it should have. But yes, that is another way how an AR can fire out of battery.0
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