AR-10 (Style Rifle) Slam Fire Lesson learned..

[B3dlam]

I just wanted to share an experince I had at the range so that others could possibly learn from it. I was performing a ladder test on my AR-10 (style rifle) chambered in 6.5 creedmoor I was well below the max pressure for the round and for some reason I hand fed the cartridge most of the way into the chamber rather then letting it strip it out of the magazine. After reading online I have realized this was not the best idea in the world. When I let the bolt slam home it slam fired before fully chambering the round causing a catostrophic failure of the case. Luckily the gun was not damaged which I will confirm with a third inspection tonight after a few days to let my nerves cool off. I will always be letting the rifle strip rounds from the magazine from here on out. This rifle is in the AR-10 Style I.E. a large framed black rifle based on eugene stoners design. It is not an Armalite Rifle model 10 which utilizes a fire pin spring to keep tension on the firing pin to prevent slamfires.

 

[ORD]

Re: AR-10 (Style Rifle) Slam Fire Lesson learned..

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: B3dlam</div><div class="ubbcode-body">I just wanted to share an experince I had at the range so that others could possibly learn from it. I was performing a ladder test on my AR-10 (style rifle) chambered in 6.5 creedmoor I was well below the max pressure for the round and for some reason I hand fed the cartridge most of the way into the chamber rather then letting it strip it out of the magazine. After reading online I have realized this was not the best idea in the world. When I let the bolt slam home it slam fired before fully chambering the round causing a catostrophic failure of the case. Luckily the gun was not damaged which I will confirm with a third inspection tonight after a few days to let my nerves cool off. I will always be letting the rifle strip rounds from the magazine from here on out. This rifle is in the AR-10 Style I.E. a large framed black rifle based on eugene stoners design. It is not an Armalite Rifle model 10 which utilizes a fire pin spring to keep tension on the firing pin to prevent slamfires.</div></div>

Not sure why all the "cloak and dagger" on not naming the brand/mfg of the rifle outright as your sig line has it clearly displayed

:

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: B3dlam Sig Line</div><div class="ubbcode-body">6.5 creedmoor, MaTen upper/lower, RR NM 2 Stage Trigger, Criterion 24" barrel, SS 5-20x50HD Scope.</div></div>

That said, glad you are ok.

 

[jwb47]

Re: AR-10 (Style Rifle) Slam Fire Lesson learned..

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ORD</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: B3dlam</div><div class="ubbcode-body">I just wanted to share an experince I had at the range so that others could possibly learn from it. I was performing a ladder test on my AR-10 (style rifle) chambered in 6.5 creedmoor I was well below the max pressure for the round and for some reason I hand fed the cartridge most of the way into the chamber rather then letting it strip it out of the magazine. After reading online I have realized this was not the best idea in the world. When I let the bolt slam home it slam fired before fully chambering the round causing a catostrophic failure of the case. Luckily the gun was not damaged which I will confirm with a third inspection tonight after a few days to let my nerves cool off. I will always be letting the rifle strip rounds from the magazine from here on out. This rifle is in the AR-10 Style I.E. a large framed black rifle based on eugene stoners design. It is not an Armalite Rifle model 10 which utilizes a fire pin spring to keep tension on the firing pin to prevent slamfires.</div></div>

Not sure why all the "cloak and dagger" on not naming the brand/mfg of the rifle outright as your sig line has it clearly displayed

:

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: B3dlam Sig Line</div><div class="ubbcode-body">6.5 creedmoor, MaTen upper/lower, RR NM 2 Stage Trigger, Criterion 24" barrel, SS 5-20x50HD Scope.</div></div>

That said, glad you are ok. </div></div>

I dub thee mr obvious lol

 

[B3dlam]

Re: AR-10 (Style Rifle) Slam Fire Lesson learned..

Lol nothing cloak and dagger about it haha there was no particular manufacture to name as for AR-10 style rifle its not a true AR-10 I was only anal about it in this post as true armalite AR-10s utilizing a firing pin spring (not sure if thats exactly what they call it) but basically a spring that keeps rearward pressure on the firing pin to prevent slam fires.

 

[ORD]

Re: AR-10 (Style Rifle) Slam Fire Lesson learned..

I know what you meant...I was just ribbing you a little for the description.

Didn't mean any ill-will toward you/your post and I am glad that neither you (most importantly) or the rifle were injured.

With that said, the Armalite pattern rifles are not immune from slam fires even with the firing pin spring although it does in fact reduce the likelihood. The Armalite design actually still allows the pin to travel forward and contact the primer, but it minimizes the amount of travel, thus reducing or minimizing the impact on the primer. If you get a soft primer, or if you chamber a round that has been chambered (but not fired) and ejected several times, the likelihood of a slam fire, even on an Armalite, increases. In any event, while the firing pin spring has its disadvantages, it is IMHO a nice "safety" upgrade versus the more common "free-floating" pins found in many AR-platform rifles/carbines.

The other part of the lesson on slamfires with ARs in addition to your info above is: 1) maintain a clean, well-lubed weapon, including insuring there is no crud or debris causing the pin to protrude any which ups the chances of a slamfire; and 2) be wary of the primer being used with the rounds you are using, especially if reloading (i.e. - federal are softer than say CCI, etc., etc.).


ETA: A member here PM'd me re: my above comment on Fed primers being softer than CCI primers. I should have probably qualified that statement a bit better than I did instead of making the blanket assertion above. In any event, that is a premise that I have operated under for some time. The following is a link to a compilation of a couple different sources about primers that you may find useful:

http://www.sksboards.com/smf/index.php?topic=56422.0

There are numerous resources concerning primers being "soft" or otherwise having "thinner" cups than others. Just be advised, especially if you are reloading, that not ALL primers were created equally.

 

[B3dlam]

Re: AR-10 (Style Rifle) Slam Fire Lesson learned..

Here are some pictures of what was left of the case. I took the rifle into work today and borescoped the chamber and it looks perfect there were a few brass shavings in the barrel extension but thats about it.

 

[rescueswimmer]

Re: AR-10 (Style Rifle) Slam Fire Lesson learned..

Glad everything worked out.

 

[showlow50]

Re: AR-10 (Style Rifle) Slam Fire Lesson learned..

ORD Thanks for the article on primers,it had great info

 

[Rprecision]

Re: AR-10 (Style Rifle) Slam Fire Lesson learned..

Where did the bullet end up ?

Make sure your bore is clear and its not jammed further down the bore ! If you thought a slam fire was fun, try pushing two bullets down the bore at the same time.

Anyways, be cautious of what primers you use, look at a light weight firing pin. Also watch your primer seating depth, a little high can cause, or promote the problem.

You have a rather special rig, in a special caliber. Its not out of reason to expect speacial considerations

 

[SPEAK338]

Re: AR-10 (Style Rifle) Slam Fire Lesson learned..

Glad to hear you are ok.
I was not aware of this possibly happening, could this happen on an AR15 also?

 

[The Gump]

Re: AR-10 (Style Rifle) Slam Fire Lesson learned..

I may have missed it in previous posts, but are your primers properly seated? Every time I clear a live round there is a mark from the firing pin on the primer. It doesn't matter if I single feed or mag feed.

I could see how the gun could slam fire if the primer wasn't seated.

 

[B3dlam]

Re: AR-10 (Style Rifle) Slam Fire Lesson learned..

The primer was seated properly.

As for the bullet it ended up downrange luckily it missed my crono never hit the target either.

As for it happening in AR-15s it can although its far less likely as the firing pin is lighter.

 

[samnev]

Re: AR-10 (Style Rifle) Slam Fire Lesson learned..

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: showlow50</div><div class="ubbcode-body">ORD Thanks for the article on primers,it had great info </div></div>

+1 Excellent article!!