AR15 firing out of battery?

[Tim Ault]

Simply put can a civilian semi AR15 fire out of battery ie: with the bolt forward but not rotated /locked into the barrel extension ? I know the hammer can drop but will it contact the firing pin or is there some kind of safety block to prevent firing out of battery.

[cdi]

If it has been built correctly and has proper parts- the firing pin will not reach the primer with enough energy (if at all) to fire out of battery.

[Hawk]

Simply put can a civilian semi AR15 fire out of battery ie: with the bolt forward but not rotated /locked into the barrel extension ? I know the hammer can drop but will it contact the firing pin or is there some kind of safety block to prevent firing out of battery.

There is nothing to block the hammer from striking the firing pin except when the body of the bolt carrier is in it's rearward position. I believe it would be next to impossible for an AR to fire out of battery. The bolt has to be collapsed to permit the firing pin to reach the primer and the shell would have to be in place under the extractor to be close enough to the face of the bolt. For both of these to happen, the bolt has to be in the locked position.

I believe a slam fire is more likely than firing out of battery.

[Boots_DE]

... The bolt has to be collapsed to permit the firing pin to reach the primer ....

Yes, the bolt must be fully in battery in order to fire. That became a problem in Viet Nam when just a little bit of dirt or crud would completely disable the rifle. That's why the forward assist was added to the design: Sometimes a little bump on the forward assist was needed to force the bolt fully into battery.

[arjohnson]

An AR15 cannot fire out of battery.

[Deleted]

If you notice... when u chamber a round into an AR you get a dimple on the primer from where the firing pin comes in contact. I never load the same AR round twice... worries me even though I have never heard of a dimpled round going off.

[tabasco_joe]

I had a batch of DPMS barrels that were slightly out of headspace. When chambering a round or a go headspace gauge the lugs engaged about 50%. (The round was a handloaded dummy.) I then put a sized case with a primer in and attempted to fire the primer. (Again no powder or bullet.) The primer had no indent marks. (There was a lot more testing and measuring between the initial headspace failure and the primer test than might be implied here.)

[Asmodeus6]

If you notice... when u chamber a round into an AR you get a dimple on the primer from where the firing pin comes in contact. I never load the same AR round twice... worries me even though I have never heard of a dimpled round going off.

Granted I do not reload. But using factory ammo I have tried to no avail to get a round to go off by chambering it repeatedly. I would chamber it, extract it. Check it against an unfired round for set back. Rechamber. Test. Rechamber. Test. etc. I probably did this full force with Federal 55gr FMJ a good 30 times. The primer "dimple" got a little deeper at first. But eventually it maxed out and I don't think the firing pin even contacted it with enough force to continue pushing it any further.

Using Russian .223. Forget it. Berdan primers aren't exactly known for being easy to set off. Something I learned all too well when building an AR chambered in 7.62x39mm. Out of the box, an IN battery strike was not setting it off. Yeah. Direct hits wouldn't set off Wolf 124gr JHP. Sometimes not even the second try. Or third... (So I grabbed a fresh round and set it off with an AK. And checked the primer 'hit' afterwards. No comparison in what "looked" like a decent hit in an AR, and what an AK does to a primer...)

Those need hit hard and pushed in deep to apply the primer into the internal anvil needed to set them off. The AK hits them HARD, and with a wider impression than does the AR.

Now if you were using particularly soft, boxer primers, at an incorrect seated depth. I could see a slam fire being possible.

I tried a similar test with Wolf 55gr FMJ - but after about the 8th chambering it set the round back when the case lost grip of the bullet. It was not worth continuing to try, in the event that it did go off. It would most likely blow my rifle apart.

I would put a $100 bill on the fact that it wouldn't go off. But not my personal safety.

[cdi]

Primer hardness is held to a strict standard on U.S. military ammo- the Russian junk ammo is not.

Repeatedly chambering the same round over and over is very likely to separate the components of the primer and cause it to fail, rather than ignite.

[ungawa]

Firing out of battery would require something strange to happen. One example would be a double feed of live rounds with soft primers. But that could happen on any semi I suppose.

Firing without 100% lockup is a different story. That can happen, and can cause results similar to OOB. Look at the people that illegally made their ARs auto during the 80s without drilling sears. Slam fires are sometimes safe and sometimes blow up your gun due to less than perfect lockup.

If you notice... when u chamber a round into an AR you get a dimple on the primer from where the firing pin comes in contact. I never load the same AR round twice... worries me even though I have never heard of a dimpled round going off.

Also something I've never seen, but a more likely consideration, is that repeated chambering can break up the primer cake to the point where it will not reliably ignite when you try to fire the cartridge. Extremely unusual but has probably happened a lot more than firing pin momentum slamfires. I remember there was a purported issue with a large batch of Hornady TAP at a PD some years ago.