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  #1  
Old 07-18-2008, 07:46 PM
D-Train D-Train is offline
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AR-15 Slam Fires

Hi everyone......I was all set to pick up a new AR-15 soon (would be my first), and then I saw a "slam fire" at the range. The gentleman who's rifle it was says that it is an inherent design flaw in AR-15's and that he sees at least 3 or 4 per month at the range. I have heard about them in the past but this is the first time I have seen one (and the scared/surprised look on the shooter's face when it happens) after shooting many of my friend's AR-15's over the past few years.

Now I'm having second thoughts.....Have any of you experienced these slam fires?

In your experience......
Which ammo has the hardest primers to prevent this?

And lastly.....
Does every round chambered get it's primer dimpled? Can this be prevented in some way?
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  #2  
Old 07-18-2008, 08:38 PM
HAIL CAESAR HAIL CAESAR is offline
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Last edited by HAIL CAESAR; 08-04-2008 at 04:50 PM.
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  #3  
Old 07-18-2008, 08:41 PM
dfariswheel dfariswheel is offline
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The gentleman who's rifle it was says that it is an inherent design flaw in AR-15's and that he sees at least 3 or 4 per month at the range.

Raw BS.
If the AR-M16 design slam fired anywhere near that much, there would be lawsuits and Congressional investigations every day.
The "usual" cause of a slam fire in ANY rifle, but especially the AR is improperly re-loaded ammo, or a defective rifle.

The AR will often leave a small dimple on the primer, AS WILL ALMOST EVERY OTHER AUTO OR SEMI-AUTO RIFLE EVER MADE.
Among the rifles that will leave a small dimple are the M1 Garand, the M1 Carbine, the AK-47, and most other such rifles.
These leave a small dimple due to the non-spring loaded firing pin.
However, the designs have such a light firing pin, there's not enough mass to allow the rifle to slam fire, UNLESS the rifle is flat out defective, badly fouled, or the ammo is improperly re-loaded.

The most often cause of a slam fire is someone re-loaded the ammo and failed to fully seat the primer.
When the bolt closes, the firing pin and/OR the bolt face hits the high primer.

The man who told you that is either a liar, a fool, or both.
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  #4  
Old 07-18-2008, 08:42 PM
wrkoster wrkoster is offline
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that's

news to me. I think most people are aware of the Garand/M1A potential to slam fire, but I've never seen an AR do it. I wouldn't recommend dropping the bolt on a round loaded (placed) in the chamber with no magazine...
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Old 07-18-2008, 08:54 PM
HAIL CAESAR HAIL CAESAR is offline
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Last edited by HAIL CAESAR; 08-04-2008 at 04:51 PM.
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  #6  
Old 07-18-2008, 10:36 PM
Cameron Cameron is offline
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All three of my ARs put a tiny mark on the primer, but my friends and I shoot ARs all the time and I have NEVER seen a slam fire in tens of thousands of rounds!
NEVER! Total crap!

Last edited by Cameron; 07-18-2008 at 10:58 PM.
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  #7  
Old 07-18-2008, 10:46 PM
DAT85 DAT85 is offline
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Quote:
Originally Posted by dfariswheel View Post
The gentleman who's rifle it was says that it is an inherent design flaw in AR-15's and that he sees at least 3 or 4 per month at the range.

Raw BS.
If the AR-M16 design slam fired anywhere near that much, there would be lawsuits and Congressional investigations every day.
The "usual" cause of a slam fire in ANY rifle, but especially the AR is improperly re-loaded ammo, or a defective rifle.

The AR will often leave a small dimple on the primer, AS WILL ALMOST EVERY OTHER AUTO OR SEMI-AUTO RIFLE EVER MADE.
Among the rifles that will leave a small dimple are the M1 Garand, the M1 Carbine, the AK-47, and most other such rifles.
These leave a small dimple due to the non-spring loaded firing pin.
However, the designs have such a light firing pin, there's not enough mass to allow the rifle to slam fire, UNLESS the rifle is flat out defective, badly fouled, or the ammo is improperly re-loaded.

The most often cause of a slam fire is someone re-loaded the ammo and failed to fully seat the primer.
When the bolt closes, the firing pin and/OR the bolt face hits the high primer.

The man who told you that is either a liar, a fool, or both.
+1,
I was a unit armorer in a Army National Guard unit in the '70 s and never even heard of such a thing even from guys who were in the Army in the "dark ages"of the early years of VN.This kind of crap gets passed around about different weapon platforms by people who want to impress others with their "knowledge"of firearms.3 to 4 times a month? BS!
DAT85
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  #8  
Old 07-19-2008, 10:01 AM
neolithichunter neolithichunter is offline
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slam fires in an ar do happen, but as mentioned, it happens do to operator error exclusively. every reason mentioned has caused slam fires in ar type of rifles. that is with the exception of single loading and dropping the bolt on a live round. the way an ar magazine works is that the round is push out of the mag to a point, then the round jumps up and is loose in the bolt raceway and chamber area. i shoot ar's in highpower and f-class, i single load all rounds as they are too long to go into the mag. also the rules require single loading of each round. after 30 to 40 thousand rounds i have fired during competitions i have only seen one slam fire at a match and it was caused by high primers. most slam fires in the above mentioned rifles though are caused by junk interfering with fire pin travel. when this happens the fire pin is stuck, sticking out of the bolt face. this usually occurs when a person has fired a high pressure round that blows the primer out of the previous round. also pierced primer can also lead to slam fires. in most cases slam fires can be traced back to poor loading and poor cleaning practices. keep it clean and use ammo in the proper pressure ranges and you will have no problem with your ar's, be sure if you reload for it to check each and every primer to make sure that is seated correctly.
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  #9  
Old 07-19-2008, 10:26 AM
NonConformist NonConformist is offline
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Yes they can happen but I have NEVER had one on three ARs and 10-15K rounds(at least)

The guy is FOS, hes either using soft primers or a titanium firing pin which is a NoGo due to that risk

Buy an AR, you wont be dissapointed


The Ar design originally had a spring around the firing pin but that was deleted and is only found on AR10s
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  #10  
Old 07-19-2008, 11:50 AM
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LW McVay LW McVay is offline
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Quote:
Originally Posted by D-Train View Post
The gentleman who's rifle it was says that it is an inherent design flaw in AR-15's and that he sees at least 3 or 4 per month at the range.
I bet he sees plenty of UFOs as well.
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  #11  
Old 07-19-2008, 12:31 PM
D-Train D-Train is offline
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Quote:
Originally Posted by LW McVay View Post
I bet he sees plenty of UFOs as well.

That was funny as H-E-double hockey stix!
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  #12  
Old 07-19-2008, 02:35 PM
Mus Mus is offline
 
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Quote:
Originally Posted by dfariswheel View Post
If the AR-M16 design slam fired anywhere near that much, there would be lawsuits and Congressional investigations every day.
Yeah the frequency seems highly overstated to me as well, but I do know there have been several improvement redesigns to the firing pin/firing pin spring setup on the AR-15 over the years to reduce the chances further still.

I havent ever had one, but I shoot mostly Q3131A with hard primers.
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  #13  
Old 07-19-2008, 03:10 PM
impalacustom impalacustom is offline
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Going to have to agree with the others, this guy is nuttier than a pet coon. I own an M1A, M1 Garand, M2 Carbine, and an AR. Never ever had a slam fire in any rifle. I use LC, commercial and reloads, no problems of any type.

I am going to write that UFO comment down, that one is priceless
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  #14  
Old 07-19-2008, 06:05 PM
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Tom Freeman Tom Freeman is offline
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If I use a Bob Sled or a single round follower like Sinclair sells *and* use Federal primers *and* trip the bolt with the muzzle level with the ground, I can induce a slam fire every time.

Change any one of the above, and I have no problems at all.

I figure its a combo of bolt velocity and primer sensitivity. For me anyway.
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Old 07-19-2008, 08:05 PM
Ironhandjohn Ironhandjohn is offline
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I once bought a used Colt SP-1 cheap because the rifle had problems. It would double-feed and occasionally 'double' fire. Replacing the FCG with new parts and replacing the extractor brought the rife to near-100% reliability.



Worn trigger parts or soft-primered ammo are the only 2 reasons I've EVER seen cause an AR-15 to double-fire. Buy one with confidence or build with good parts. The guy at the range is full of crap, IMHO....
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  #16  
Old 07-21-2008, 12:40 PM
30Cal 30Cal is offline
 
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I've seen in an AR. Dropped the bolt and bang. Handloads.
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  #17  
Old 07-21-2008, 03:22 PM
Ron H. Ron H. is offline
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Sir, I've seen two ARs fire on bolt closing at high power matches. One was a handload with a high primer; don't know what caused the other.

Hope this helps, and Semper Fi.

Ron H.
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  #18  
Old 07-21-2008, 03:54 PM
ben589 ben589 is offline
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I've got a .50 Beowulf built on an AR platform that I've noticed dimpled primers on, but have never had a slam-fire.
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  #19  
Old 07-22-2008, 03:40 AM
Chieftain Chieftain is offline
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I served in a sister unit to the one the author did. I chose to stay for an additional tour.

Most of the problems the author talks about, I witnessed too.

So before you holler BS. Check your facts.

The AR15/M16/M4 of today IS a better rifle than the E1 models we were issued and carried in 1967, but I will not own one. I will not own a widow maker.

Part I
http://www.jouster.com/articles30m1/index.html
Part II
http://www.jouster.com/articles30m1/M16part2.html

I lived this. It is not second hand to me.

Go figure.

Fred
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  #20  
Old 07-22-2008, 10:54 AM
Alabam Alabam is offline
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Has anyone tried chambering the same round over and over to see how many times it takes before it goes off?
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  #21  
Old 07-22-2008, 07:36 PM
dfariswheel dfariswheel is offline
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Probably 100's???.
When the AR, like most all semi and full auto rifles leaves a dimple on the primer, it's not a big, deep dimple.

What you get on a non-defective rifle is an extremely shallow, tiny impression, not any kind of real crater.
Since no one but a fool would intentionally chamber a rifle round more than a few times before expending it, there's little chance of it firing from repeated chambering.
Again, as in most such rifles, the firing pin is extremely light, specifically to prevent a firing pin induced slam fire.

Per the original poster "IS this a defect in the AR-M16 series rifle"?
If it is, it's a defect found in virtually every military and many commercial rifles made since the 1930's.
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  #22  
Old 07-22-2008, 08:19 PM
tcotariu tcotariu is offline
 
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Durring 6 years in the Army I never saw one.
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  #23  
Old 07-22-2008, 08:46 PM
devildog66 devildog66 is offline
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Why Of Course, My Name Is Joe Izusu...

Yep, the AR platform is prone to slam fires when well-maintained and using modern ammunition (most of 'em out there), the 1911 will discharge a round when dropped AGAINST ANYTHING, and the M9 will crack its slide after 1000 rounds of M882 ammo.

Can somebody help me? My tinfoil hat fell down over my eyes again from the rotor wash after the black helicopter flew over...


Sorry for the sarcasm and it is not directed to the original poster but just to the tired notions that keep getting passed around as gospel truth.

Sorry about the misspelled Isuzu...
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  #24  
Old 07-24-2008, 02:22 AM
impalacustom impalacustom is offline
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Cheiftan, it is not my place to call you a liar or anything but I can say that my dad didn't experience any of the trouble with his M16 in Vietnam that you did. He was in the 1st/7th and deployed to Vietnam with an M14 in 67 and that was immediately replaced with a new M16 as soon as he got there.
The only things he ever said that was a problem was that he had a round cook off from firing it in auto and it got hot and lit the round off after he closed the bolt from a new magazine. It was raining and was sizzling the rain off the barrel and breach. He pulled the charge handle back many times and was going to get out his cleaning kit to knock out the brass but it finally gave and pulled out with the extractor. I have asked him many times how clean he kept it and he told me that there were times it was so dirty that the bolt wouldn't cycle and thats when he cleaned it.
His main complaint was it didn't have the knockdown power of the M14, but he loved it..

There was a really good article in last months Leatherneck about the new rifles from a Gunnery Sargent and his take on the M16/M4.

If you are getting a slam fire try a Ti firing pin, I have one in my M4 and it works great, no dent or anything.
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  #25  
Old 07-28-2008, 11:54 AM
mr1911 mr1911 is offline
 
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Quote:
Originally Posted by dfariswheel View Post
The gentleman who's rifle it was says that it is an inherent design flaw in AR-15's and that he sees at least 3 or 4 per month at the range.

Raw BS.

The "usual" cause of a slam fire in ANY rifle, but especially the AR is improperly re-loaded ammo, or a defective rifle.

The man who told you that is either a liar, a fool, or both.
I also agree,......total idiot jackass, an AR15/M16/M4 will only "slam fire" if the idiot has a malfunctioning or improperly built gun,......

"Cook offs" do happen in heavy commbat whith sustained full auto fire but are still fairly rare.

Last edited by mr1911; 07-28-2008 at 11:57 AM.
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