SRT Driver Posted October 2, 2007 Share Posted October 2, 2007 To the AR gurus: Is it possible for an AR to fire out of battery? Link to comment Share on other sites More sharing options...
cking Posted October 2, 2007 Share Posted October 2, 2007 yes Link to comment Share on other sites More sharing options...
Patrick Sweeney Posted October 2, 2007 Share Posted October 2, 2007 If you only looked at the mechanicals, you'd have to say no. But since more than one person has experienced the joy of an out-of-battery discharge, it happens. How, it isn't really clearly known. Suppositions, conjectures, etc. But no "Do A-B-C and you'll have an o-o-d." Why do you ask? Link to comment Share on other sites More sharing options...
Carlos Posted October 2, 2007 Share Posted October 2, 2007 Hypothetical: if the AR firing pin becomes lodged forward (due to brass shavings, fouling, pierced primer, or some other cause) could a protruding firing pin set off a round before the gun goes into battery? Another possibility: Ever noctice the nice dent in the primer from the last round fired after "unload and show clear!" ?? There is no FP spring. Could an AR slam fire with, maybe a Federal small rifle primer? If it slam fired, would it do it in battery? Link to comment Share on other sites More sharing options...
rvb Posted October 2, 2007 Share Posted October 2, 2007 (edited) I'm far from an AR expert (but I have built a few) and I'm going from memory here, but it seems an in-spec FP can't stick out of the breech face until the bolt has entered the barrel extension and cammed enough for the bolt-carrier to go forward enough for the FP to stick out. So mechanically it can only be fired in battery, even w/ a slam fire. This doesn't mean rounds can never go off out-of-battery... I'm guessing 'oob' most likely happens as a result of 1) high primer, 2) debree of some sort getting between the bolt/primer, or 3) an out of spec or broken FP. -rvb Edited October 2, 2007 by rvb Link to comment Share on other sites More sharing options...
GentlemanJim Posted October 2, 2007 Share Posted October 2, 2007 the firing pin cannot stick and still allow the bolt to open. when the bolt is open the FP is pulled to the rear and will not protrude...unless broken in half. Lots of what ifs would have to pile up to have it fire out of battery. I am no expert !! but I have been building them and shooting them for 30 years....never seen it happen...but it could be possible. Jim Link to comment Share on other sites More sharing options...
Carlos Posted October 2, 2007 Share Posted October 2, 2007 the firing pin cannot stick and still allow the bolt to open.will not protrude...unless broken in half. Thanks Jim! Well the "jammed firing pin" theory is out. Broken firing pin is in. Slam-fire should be out too. Have never seen an out of battery fire. As far as AR kb!s seems that mostly the bolt is jammed in place & the carrier splits the upper like a clam shell. But that event has no relation to an oob. Link to comment Share on other sites More sharing options...
SA Friday Posted October 2, 2007 Share Posted October 2, 2007 Slam Fires are DAMN hard to reproduce even with a freefloating firing pin. I ran a case where a guy shot his buddy accidently at the range cleaning area and claimed mechanical failure of the gun. The lab tested it and said no way, but their documentation was crap. So, I took it to the range and ran a HUGE battery of tests on the actual weapon. M-16 A2 with no internal modifications, not even polishing of parts and it was fairly new. A few basic external mods, but nothing that factored. I tried everything I could think of and no fricken way. Now this was with standard issue military ammo, but I highly doubt this would have even lighted off a soft fed primer based on the firing pin markers. Link to comment Share on other sites More sharing options...
Craigar45 Posted October 3, 2007 Share Posted October 3, 2007 I have often wondered if a very soft small pistol primer might be fired oob in an AR... Is the light strike caused by chambering a round created in or out of battery? Somewhere in between? Hmmm... C Link to comment Share on other sites More sharing options...
rvb Posted October 3, 2007 Share Posted October 3, 2007 (edited) I have often wondered if a very soft small pistol primer might be fired oob in an AR... Is the light strike caused by chambering a round created in or out of battery? Somewhere in between? Hmmm...C re-read my post (#5). The FP cannot stick through the breech face until the bolt has cammed significantly into the barrel extension (in battery, lugs engaging). Try it... disasemble your AR leaving the bolt/carrier group together. push fwd on the FP. The FP will not stick out until you have pushed the bolt significantly into the carrier. -rvb Edited October 3, 2007 by rvb Link to comment Share on other sites More sharing options...
EricW Posted October 3, 2007 Share Posted October 3, 2007 Is there a documented instance of OOB firing occuring? How would one tell the difference between OOB and an overcharge? Just curious. Never even considered the possibility on an AR before. Link to comment Share on other sites More sharing options...
Joe4d Posted October 3, 2007 Share Posted October 3, 2007 Yep,,, out of battery firing seen it happen, with an undamaged rifle, a bent round, slap, pulled, soldier didnt observe, and bang on the release, round was bent and partially chambered, best I could figure the corner of one of the locking lugs hit the primer, Link to comment Share on other sites More sharing options...
rvb Posted October 3, 2007 Share Posted October 3, 2007 (edited) Is there a documented instance of OOB firing occuring? How would one tell the difference between OOB and an overcharge? Just curious. Never even considered the possibility on an AR before. I have No idea on either question! I can "imagine" a round going off out of battery if the primer was way high [edited to add: or the round is way fubar'd as Joe mentioned] and the bolt itself sets it off.... 'oob' can be an issue on pistol-cal ARs... if it doesn't chamber all the way, the FP CAN poke through the breech face. I've seen photos where people claim that's what happened on 9mm guns... Edited October 3, 2007 by rvb Link to comment Share on other sites More sharing options...
GentlemanJim Posted October 3, 2007 Share Posted October 3, 2007 I have often wondered if a very soft small pistol primer might be fired oob in an AR... Is the light strike caused by chambering a round created in or out of battery? Somewhere in between? Hmmm...C re-read my post (#5). The FP cannot stick through the breech face until the bolt has cammed significantly into the barrel extension (in battery, lugs engaging). Try it... disasemble your AR leaving the bolt/carrier group together. push fwd on the FP. The FP will not stick out until you have pushed the bolt significantly into the carrier. -rvb The bolt will be fully engaged in the lugs ...and at full rotation way before the carrier comes fully forward to a position where the firing pin can protrude. any firing out of battery would be a result of something other than the firing pin. lighting off a round during load or unload CAN happen...as with ALL mechanical devices....SH$% can happen. Jim Link to comment Share on other sites More sharing options...
want2race Posted October 6, 2007 Share Posted October 6, 2007 Broken cam pin, all stars in the sky aligned just right.... I've seen a few aftermaths myself. The last one I saw, the empty case was still lodged in the chamber. It was not fully seated and had a blow out at the 7 O'clock position (partially ruptured case). Split the upper. Broken cam pin. Did it break before or after KaBoom? Exactly. Replace your cam pins if you see a shoulder starting to wear from the bolt carrier. Cheap insurance. Link to comment Share on other sites More sharing options...
wsimpso1 Posted October 17, 2007 Share Posted October 17, 2007 While the AR is pretty well designed to prevent OOB firings, there have been enough reports to make me believe that they have occurred. The most plausable (to me) explanations involve debris in the firing pin hole from damaged primers and/or case shavings off of sharp corners on the ejctor hole or extractor being likely source of debris. I have personally seen a bolt (High Power shooter trying to get more velocity than is reasonable) with more than one little slug of brass extruded from primers stuck in the firing pin hole. When the gun tries to close on a subsequent round, the debris makes the bolt act like it has a fixed firing pin while also preventing the bolt from running far enough forward to allow lockup. There is your OOB firing opportunity. Broken firing pin or broken cam pin are other possibilities, but I think that they are lower likelihood events than debris. The broken firing pin would still need to be jammed forward to work its magic, which would mean case and/or primer debris anyway. When a cam pin breaks, it is usually in the middle, at the firing pin hole, and will continue to work more or less normally until it ties up the whole works. The cam pin would have to break on both ends at the junction between the bolt and the carrier, a highly unlikely event. Billski Link to comment Share on other sites More sharing options...
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