AR Slam Fires Fact vs Fiction

Have you personally experienced a slam fire with any of these primers?

  • CCI Small Rifle Primers 400

    Votes: 3 2.5%

  • CCI Small Rifle Magnum Primers 450

    Votes: 1 0.8%

  • Remington 7.5 Small Rifle Primers

    Votes: 2 1.7%

  • Federal 205 Small Rifle Primers

    Votes: 4 3.4%

  • Winchester Small Rifle Primers

    Votes: 4 3.4%

  • Other

    Votes: 4 3.4%

  • None

    Votes: 110 92.4%
  • Total voters
    119
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AgPilot said:
My 308 was fine until I screwed a Silencer on it. Now it is slam firing. (Factory Ammo at the moment). Going to see a Gun Smith then start loading hand loads.
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Well, you have the turn thing for the air-fuel, pull that out, adjust a turn left, and the gas valve for the fletzer on that automatic feedback. Best to turn them down a bit. Check the B&C bearings.

Dammit. edited to add not Left: COUNTER CLOCKWISE,
 
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Slam Fire- AR15 - 5.56/223

A target trigger causes the so called slam fires when set to light. Hammer is delayed when it slips off the sear.

Letting the bolt slam into a round already chambered, can do it, more so on mismatched parts guns. This can set the shoulder back, if head to datum is to long. High primer not good.

The bolt has to be locked for the gun to fire.
 
I've personally had none, but I have been on the line at 2 or 3 High Power matches in the last 5 years where another shooter has had a slam fire, each time during single loading.
 
^^ Nearly as much fun as the guy next to you unintentionally flipping the switch to the third position on 100 meter line. In a leg match.
The rest of the line chuckling through the string of fire.

No, slamfires are not fun.
 
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Charlie98 said:
Do you know of any OOB events directly cause because of a worn safety bridge? I know that is a theory...
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The receiver bridge was and always was, a firing pin retraction bridge. I am of the opinion that calling it a "safety" bridge is a creation from the late 50’s to early 60's. The Army and its more Khaki than Khakis stooges in the NRA created a misdirection from the most common cause of slamfires: sensitive primers. The receiver bridge is not a positive firing pin block, nor was it ever meant to be. This is an M1 carbine turned upside down. Incidentally, in the M1 carbine TM I have, the receiver bride is called a firing pin retraction cam.

mNJCiLD.jpg

1ejo6oy.jpg



I examined John Garand's' patent, the functions of the firing pin tang and the firing pin retraction bridge are explicitly spelled out and not as a firing pin block. Its primary function is to retract the firing pin at unlock. There is a slot allowing the firing pin to go forward when the bolt is in battery, but the function of the whole as a firing pin block is not claimed. The extractor is claimed as a means of holding the firing pin.

Patent 1 892 141 Semi Automatic Rifle. J. C. Garand Dec 27 1932

The firing pin is formed at its rear end with a laterally extending had 72 adapted to contact a projection 73 formed in the receiver when the bolt is in unlocked position so that the firing point is retracted into the bolt, but the head is cut away at 74 to pass such projection when the bolt is locked to permit the pin to be moved to its extreme forward or firing position.

"I claim":

5. The combination with a gun provided with a receiver, of a bolt receiprocable in the receiver, a firing pin reciprocal in the bolt, a laterally extending head for the pin and means in the receiver to engage the head on rocking of the bolt to unlocked position to retract the pin

6. The combination with a gun provided with a receiver, of a bolt reciprocable in the receiver, a firing pin in the bolt, an extractor carried by the bolt, and means on the extractor to prevent rotation of the pin with respect to the bolt.

7. The combination with a gun provided with a receiver, of a bolt reciprocable in the receiver, a firing pin in the bolt, an extractor carried by the bolt, and means on the extractor cooperating with the pin to limit movement thereof.

8 The combination with a gun provided with a receiver, of a bolt reciprocable in the receiver, a firing pin in the bolt, an extractor carried by the bolt, and means on the extractor to limit reciprocatory movement of the pin with respect to the bolt and prevent rotary movement thereof with respect thereto.

If John Garand could have claimed the receiver bridge as a firing pin block, he would of claimed it in his patent. The Garand mechanism controls slamfire rates by primer insensitivity.
 
cfullgraf said:
I've used all the primers listed except the Federal. Also, I've used CCI#41. I've never had slam fire in an AR-15 yet.

I have AR-15's in several different cartridges from 17 Rem to 300 Blackout.

High primers must be avoided. They have been known to be a cause of slam fires.
Click to expand...
 
The only primer I haven't used consistently is the Remington SRP, and thus far I haven't had a slamfire in several thousand loads in the AR platform. Due to the shortage of primers I recently have successfully tried SPMagP (CCI, FED, and WIN) in the 5.56 and 300AAC. So far I have had zero issues of slamfire, squib, reduction in velocity, or signs of abnormal pressure. This is NOT an endorsement to any component or method. I am simply relaying some of the material and methods that I have tried. Do not try them if you have ANY reservations or concerns. That said I urge each reloaded to use the published data for their reloading efforts. I fully intend using SRP's again when they come available (hopefully at an affordable price).
 
sfl_gunner said:
So I've heard a ton of stories about different primers being prone to slam fires in the AR platform. The most common on are CCI small rifle primers I keep hearing these are a no go in the AR platform. I have fired hundreds of thousands of rounds through AR platforms. I have only experienced 2 slam fires. One using Winchester SRP and one using Remington 7.5 SRP. Both of these instances were when I was single loading the rifle not fed from a magazine. With the Remington I'm fairly certain the primer was high, with the Winchester I don't know what caused it.

What are some of YOUR experiences? (Not what have you heard from your cousin.)
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I built and rebuilt M16's in the USAF and have put over 100k rounds through civilian market AR's. I have never experienced a slam fire. That's not to say they don't exist, just that I have never experienced one and a quick query of friends (shooters) have never experienced one either.
 
I've fired a number of rounds through several AR's from cheap to expensive. While likely not as many rounds as others have sent. I have to say I have never experienced a slam fire. I have never single loaded my AR's however, and have always used the charging handle or the bolt catch to load a live round.

I've loaded with Remington, Winchester, and CCI small rifle primers both magnum and regular.
 
anothernewb said:
I've fired a number of rounds through several AR's from cheap to expensive. While likely not as many rounds as others have sent. I have to say I have never experienced a slam fire. I have never single loaded my AR's however, and have always used the charging handle or the bolt catch to load a live round.

I've loaded with Remington, Winchester, and CCI small rifle primers both magnum and regular.
Click to expand...
 
Had one once, years ago, standing offhand, single load...round dropped in chamber, bolt released from mag-catch...10 points in the dirt. Always thought it was a high seated primer...noticing a pattern of single load, bolt released...
 
Klaatu Barada Nikto said:
I built and rebuilt M16's in the USAF and have put over 100k rounds through civilian market AR's. I have never experienced a slam fire. That's not to say they don't exist, just that I have never experienced one and a quick query of friends (shooters) have never experienced one either.
Click to expand...

Slamfires are statistical. Lots and lots of slamfire reports out there in AR's. It was not until the M16 was type classified and put into the field was the problem of slamfires in the gun recognized. And then the Army modified the rifle to a lighter firing pin, which is shown in the lower picture

oMfXCL8.jpg

Lets play a game. You got an AR10? Use Federal primers and take out the firing pin spring.

fM6Qc9S.jpg

that spring is only there to reduce the frequency of slamfires. Take that spring out, use the most sensitive primer on the market (Federal) , and point the muzzle down at the ground, the more perpendicular the better, drop a round in the chamber, and hit the bolt release. I predict given enough tries, you will experience a slamfire. Slamfires will shake you up.
 
Slamfire said:
Slamfires are statistical. Lots and lots of slamfire reports out there in AR's. It was not until the M16 was type classified and put into the field was the problem of slamfires in the gun recognized. And then the Army modified the rifle to a lighter firing pin, which is shown in the lower picture

View attachment 1038324

Lets play a game. You got an AR10? Use Federal primers and take out the firing pin spring.

View attachment 1038325

that spring is only there to reduce the frequency of slamfires. Take that spring out, use the most sensitive primer on the market (Federal) , and point the muzzle down at the ground, the more perpendicular the better, drop a round in the chamber, and hit the bolt release. I predict given enough tries, you will experience a slamfire. Slamfires will shake you up.
Click to expand...

They were all modded with the lighter firing pins in 1975 when I went into the AF.
 
I had one the other night, Very disturbing. I was having some trouble with a few reloaded 458 SOCOM rounds that were sticking in the chamber on a new rifle build. So I had been checking the individual shells to make sure all were chambering and more importantly not sticking on extraction by manually cycling them, then manually ejecting them. I had done this in the past. I had gone through the whole bunch with one that was a bit hard to cycle out so I decided to re check, The bolt was held open as happens when the last shell is cycled out of the magazine and since it was a single shell I just hand chambered it. I then just released the bolt on the round already in the chamber. That turned out to a really bad idea! I assume the inertia of the bolt going forward caused the floating firing pin to advance with enough force to just slightly dent the primer. It seems to me now to be a very dumb idea, but I had never heard of a problem doing this before nor had I had an issue in the past 15 or so years. I was using CCI magnum pistol primers as called for, and they were seated properly, The gun was on safe which means nothing really in this circumstance. Won't be doing that ever again. Another good reason why a gun should never be pointed in a unsafe direction. EVER. After some research I see where this issue is well known and is the reason for the existence of the thicker cupped military type primers. But I have never seen this type of primer listed for the large magnum pistol primer used in the 458 SOCOM. Since it is technically a military round, although with pretty limited usage, I wonder if such primers do exist. I am sharing this embarrassing circumstance to hopefully prevent it from happening to anyone else reading this..
 

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This is an old thread that been awakened.

Despite what some people think Slam Fires DO HAPPEN. I've had it happen on my 458 SOCOM and my AR-10 in 6.5 CM. The fix is to go with the HP FP & BCG from JPI in the AR-10. This pin is lighter, smaller in dia and is designed for higher pressure rounds. If your having primer flow with you over sized primer hole BCG this fixes all the problems.

I always test by dropping a live round into the chamber and let the bolt fly from the release. My 6.5CM (ar-10) would set of Federal LR 4 out of 5 times. And some times when fed from a magazine. If you use the Fed's designed for AR NO problem. But std primers will always have a better chance of slam fires.

I believe someone makes a return/rebound spring to fit AR's but I have not tried them since I normally use AR primers.

With the 458 SOCOM since you were having chambering problems the round was tight so it could not move, made it more likely. Loading from a magazine it can still happen but is a much lower chance due to the bolt velocity being reduced.

The 458 SOCOM is a low pressure (35k) round the reason a pistol primer is used, and handgun powder. During the wildcat stage it was recommended only to use CCI LPM primers, not Win (brass) for it was more sensitive and never a Fed. The older Ni plated LP from Win was said to be good.
 
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